Because these trains only depart once per day, they can be hidden on the ticket booking sites and journey planning apps - particularly if you don't remember to tick an often optional 'direct trains only' box when looking up a journey.
Hence ShowMeTheJourney thought it would be a good idea to bring them to the surface and shine a spotlight on them, as the more people which travel by these trains, the less likely it is that they'll disappear completely.
That some of these daytime journeys are even possible may be a pleasant surprise, while on other routes you may you may be shocked to discover how infrequent the train service is, but 1 x train per day is obviously better than no service at all.
This is the only direct train service, day or night between The Netherlands and Switzerland.
Heading south, the swish ICE train is usually scheduled to depart daily from Amsterdam at 08:08, from Utrecht at 08:37 and from Arnhem at 09:07, with an arrival in Basel at 14:34.
It terminates at Basel SBB station where straightforward connections are available on to a swathe of other Swiss destinations including Bern, Lugano, Luzern, Interlaken and Zurich.
It is also the only direct train between The Netherlands and both Karlsruhe and Freiburg (Breisgau).
Heading north the train is usually scheduled to depart from Basel at 15:13 and arrive in Amsterdam at 21:58 - connect in Utrecht for Den Haag/The Hague and Rotterdam.
There are 2 - 3 high speed AVE trains per day from Barcelona to Sevilla/Seville and they're more than twice as fast as this daily IC (Talgo) train - which is usually scheduled to depart from Barcelona at 09:30.
But if you will be booking tickets less than a couple of weeks ahead, those AVE trains also tend to be around twice the price.
Another plus of making this epic 11 hour journey on this IC (Talgo) train, is the greater opportunity to experience the beautiful Spanish landscapes.
It's also the only direct train between both Barcelona/Sevilla and Albacete - heading north it is usually scheduled to depart from Sevilla Santa Justa station at 08:35 and from Cordoba at 09:45.
Though reflecting the fact that it is a cheaper alternative to those AVE trains, ShowMeTheJourney's understanding is that unlike other Spanish Talgo services, this train does not convey 'Preferente'/1st class.
There are 3 x EC trains per day which leave Basel and call at Bern and Domodossola, but there is only 1 x Swiss IC train.
It is scheduled to depart from Basel SBB station daily at 10:31 and from Bern at 11:24 - and what earns it a place on this list is its convenience for Swiss Travel Pass users.
Those passes, along with Swiss Day Passes, can be used on this train, despite the fact that it heads over the border to Italy.
At Domodossola easy connections are available into the 'Centovali Express' trains to Locarno, on which Swiss Travel Passes are also valid.
Or if you will be heading to Italy with an InterRail or Eurail Pass and want to avoid the rail pass reservation fees, which are payable on those EC trains, you can take this train and connect in Domodossola for a Regionale train on to Milano.
Note that there isn't a Swiss IC train in the opposite direction from Domodossola to Basel.
Long distance international train services in eastern Europe tend to operate to particularly sparse timetables.
The one train per day between Wien/Vienna and Beograd was also going to be included on this list, but it's been suspended during 2020 due to work to upgrade the railway line in Serbia.
This train named the 'Traianus' is scheduled to depart daily form Budapest Keleti station at 07:10 and sets off on a journey of more than 16 hours to the Romanian capital.
It's a fascinating, but not particularly scenic or luxurious train ride, but if you want to head on by train in the summer time towards Istanbul, then it can be a better option than taking the overnight train from Budapest.
However, it seems as though what had been a summer only tightly timed connection, into that train on to Istanbul won't now be available when taking this train.
This is the only direct daily direct train between Koln/Cologne and Salzburg, but this train also fulfils another function.
It connects the two spectacular landscapes of The Rhine Gorge and the Wörthersee - both of which can be fully appreciated from the train, which is why it is included on our list of Europe's Most Epic Express Train Journeys.
Heading south the train, which is named the 'Worthersee' and conveys a restaurant car, is usually scheduled to depart from Dusseldorf at 07:51, from Koln Hbf at 08:18 and from Koblenz at 09:18.
It is due into Salzburg at 15:59 and into Villach at 18:43 from where connections are usually available on to Lesce-Bled and Ljubljana.
It also makes calls at three resort towns on the shore of the Worthersee in Velden, Portschach and Krumpendorf, before arriving in Klagenfurt.
Heading north the train is usually scheduled to depart from Klagenfurt at 08:42 and from Salzburg at 12:00.
A TGV train provides the only train service between central Germany and the south of France, because a series of high speed lines has made this routing feasible.
Heading south the train is usually scheduled to depart from Frankfurt (Main) at 13:58, in good time for connections to be possible from all the major cities to the north, including Berlin, Hamburg and Koln/Cologne.
This train, which also calls at Mannheim, Karlsruhe and Baden Baden, is due into Avignon at 21:08 and Marseille at 21:46 - in time for a connection to Toulon, but it isn't possible to travel farther to the east.
Heading north the train departs from Marseille between 08:00 and 08:15 - though worth knowing is that it departs from Marseille too early for connections to be possible from destinations on the French Riviera such as Antibes, Cannes or Nice.
It is also scheduled to call at Aix-en-Provence TGV station (08:29) and Avignon TGV station at 08:51 - and is usually due into Frankfurt (Main) at 15:58.
Most of these solitary daily trains are rare survivors, left over from before the dawn of the high speed train age and its associated reduction in the number of long-distance conventional train services.
But this routing is a welcome recent addition to the timetable, restoring a direct daytime train service between central Germany and northern Italy, which had disappeared for more than 15 years - though there are still no overnight trains between Frankfurt (Main) and Italy.
Though what's unusual is that the southbound and northbound trains between Frankfurt and Milano take different routes.
The train which departs daily from Frankfurt (Main) at 08:01 takes the highly scenic Gotthard route in Switzerland and travels via Luzern, Lugano and Como - so if you will heading back to Germany from these cities, you will need to make a comparatively straightforward connection at Basel SBB station.
The train that heads north from Milano at 11:23, takes the route through The Simplon and Lotschberg Tunnels, so it calls at Stresa on Lake Maggiore, Brig, and Bern - providing these locations with a direct link to, but not from, Frankfurt.
So when heading south from Frankfurt to these destinations, you still have to make connections in easy to use Basel SBB station.
The trains used for this service have restaurant cars.
Six trains per day take a beautiful route through the Elbe River valley and connect the Berlin with Praha/Prag/Prague, three of these trains commence their journeys in Hamburg, while another calls in Hamburg on route from Kiel.
But only one of the trains from Hamburg via Berlin and Dresden continues its journey beyond Praha, to travel across Czechia to Brno and then on to Bratislava and Budapest.
This train, which is named the 'Metropol' and comprises newly updated Hungarian railway coaches including a restaurant car, departs daily from Hamburg Hbf at 06:48 and from Berlin Hbf at 08:59 - and arrives in Bratislava at 17:50 and Budapest at 19:20.
Similarly when travelling north, seven x trains per day link Budapest to Praha/Prag, but only one train, which departs from Budapest at 07:40 and calls in Bratislava at 10:10, travels beyond the Czech capital to arrive in Dresden at 16:43, in Berlin at 18:41 and at Hamburg at 21:15.
This is the only train service which links both Hamburg and Dresden with Bratislava and Budapest, but there is now a relatively new overnight train service between the German and Hungarian capitals, which takes a different route - from Berlin and from Budapest.
Landscape lovers need to know about this train, not only does it connect the beautiful Tyrol area of Austria to the Upper Middle Rhine Valley in Germany, it's the only railway service which travels on both the incredible Arlberg pass and Rhine Gorge routes.
This daily train service is named the 'Bodensee' as it connects the cities of the Rhine-Ruhr with two towns on the shore of this popular lake destination - Bregenz and Lindau.
Though due to works on the railway line in southern Germany, this service is only scheduled to depart from and arrive at Innsbruck between mid-July and mid-September in 2019 - at other times the train will only be operating Stuttgart ↔ Dortmund.
Heading north it usually departs from Innsbruck at 08:54 and also calls at Landeck, St Anton, Feldkirch, Bregenz and Lindau, in the opposite direction it is usually scheduled to depart from Koln/Cologne hbf at 09:18 and from Koblenz at 10:16.
What's being forgotten in the understandable excitement surrounding the revamped Caledonian Sleeper services is that you don't have to travel overnight when taking a train between London and the Scottish Highlands.
A daily train service operated by LNER, which is evocatively named the 'Highland Chieftain departs from London's Kings Cross station at noon and heads for Perth, Pitlochry, Kingussie, Aviemore and Inverness - where it is scheduled to arrive at 20:08.
And for most of the final five hours of its journey, once it has passed Durham, it travels through a stunning landscape, which can't be seen from the overnight train.
Though you need to be sat on the right hand side to see the best of the views - AND travelling when days are at their longest, in order to be able to appreciate the stunning Highland scenery.
Heading south you can take in the scenic highlights year round, as the train is scheduled to depart from Inverness at 07:55 and arrive in London at around 15:50.
A suprsingly spare service of only 4 - 7 trains per day use the high speed cross border line between France and Spain - and only one of these daily trains provides a direct link between French cities and the Spanish capital, Madrid.
All seats are assigned on this train, which is usually scheduled to depart from Marseille at 08:01- and if you looked at a map, you would probably conclude that you'd want your reserved seat to be on the left - because from that side of the train you can see the sea.
However, it's the seats on the right hand side, which give the only direct rail journey from the south of France to the Spanish capital a wow factor.
That's because for much of the French part of the journey, between Sète and Perpignan, the railway line travels a series of lagoons, which bring the sea inland.
It's this combination of marine landscapes and high speed travel at more than 290 km/h, which makes this journey unique.
Though when travelling east from Madrid, you need to be travelling when days are at their longest to experience the best of this journey.
This train is usually scheduled to depart from the Spanish capital at 13.35, so in this direction, it doesn't travel by the Mediterranean shore until after 18:00.
We've cheated slightly as there are 2 x trains per day on this route at weekends, but only 1 x train operates in each direction on Monday - Friday.
ShowMeTheJourney particularly wanted to include it on this list because when I last travelled on this route from Munchen to Verona, I was sharing a compartment with five other travellers who were all heading on to Venezia, but had no idea that a direct train to there from Munchen was an option.
This train is usually scheduled to depart daily from Munich/Munchen at 11:34 and from Innsbruck at 13:24 - at weekends there is an additional departure from Munchen at 07:34 and from Innsbruck at 09:24
Heading north the daily train is usually scheduled to depart from Venezia S. Lucia station daily and also at 15:35 on weekends.
Not only does this train link two of Europe's must see destinations, hence its inclusion on two of our suggested rail pass itineraries - it's also featured on our list of Europe's Most Epic Express Train Journeys.
This train is the only direct daytime train service between Germany and Salzburg and both Slovenia and Croatia.
If you would ordinarily baulk at the prospect of spending more than 8 hours travelling by train, this journey has the potential to shatter perceptions.
The 6hr 40 min section of the journey between Salzburg and Zagreb is particularly stunning and has earned this train its place on ShowMeTheJourney's list of Europe's Most Epic Express Train Journeys.
Though when heading south, if you want to experience this journey at its best you'll need to be travelling when days are at their longest, because the train isn't due into Zagreb until 20:51.
The train is usually scheduled to depart from Frankfurt (Main) at 08:20; from Munchen/Munich at 12:17 and from Salzburg at 14:12.
Heading north you can't help seeing the best aspects of the journey as it is due to depart from Zagreb at 06:55 and from Ljubljana at 10:17.
There is also an overnight train on this route and it is usually scheduled to depart from Munchen/Munich at 23:35 and from Zagreb at 21:23.
There are up to 8 x trains per day between Paris and Nice, but only of these departures - the train which is usually scheduled to leave Paris daily at 15:07, travels beyond Nice to Monaco-Monte Carlo and Menton.
Heading north to the capital, it is due to depart from Menton at 09:22 and from Monte Carlo at 09:31.
The northbound train also has two advantages over the train which heads south:
(1) On Mondays-Saturdays it's possible to connect into this train from towns on the Italian Riviera, by making connections in Ventimiglia and Menton
(2) You can appreciate the full extent of the stunning Cote D'Azur scenery - one of the highlights of the train ride will be the first part of the journey between Menton and Nice.
Only one daily train connects this gateway city in Italy to the Adriatic Coast, but on the most recent Italian train timetable, this service was transformed for the better.
Because the train which sets off south from Torino daily at 09:20 and north from Lecce at 12:06 and Bari at 13:32, is now a Frecciarossa train - so it can travel at more than 280 km/h on the high speed lines between Torino/Turin and Bologna.
Though the scenic highlights of the trip come between Rimini and Bari, when the train travels right by the beaches on the Adriatic coast.
But only daily daytime travels the full length of the Norway's longest railway route - the Nordlandsbahnen - it departs Trondheim for Bodø daily at 07:38 and heads south from Bodø at 12:25.
More information is available on The Guardian's website's list of its favourite worldwide railway journeys
There is also an overnight train between these two cities and if you travel by it at the height of summer, you won't have to take these daytime trains in order to appreciate the spectacular journey by daylight.
Look at a railway map of Europe and there is a tantalising railway line along the northern half of Italy's Mediterranean coastline, which connects Ventimiglia on the French border with Roma/Rome.
There is only one daytime train, which operates along the length of this route and avoids the need to change trains in Genova.
Heading south it is scheduled to depart from Ventimiglia at 06:41, so before any train has crossed over from the French side of the border - and then calls in Sanremo/San Remo at 06:58, Albenga (07:37) and Savona (08:05).
For the first 3hr 30mins of its journey, from the right, it offers spectacular views over the shoreline until it arrives in La Spezia.
So the early start is rewarded by being able to see these views by daylight - the train is due to arrive in Roma at 14:33.
It heads north from Roma at 15:57, so in this direction it travels along the coast at dusk or in darkness.
There are many evocatively romantic train journeys which can be taken from Vienna, but of those, this is one of the most scenic options.
This train, named the 'Emona' is scheduled to depart daily from Wien/Vienna Hbf at 07:58, but you will be amply rewarded for making that early start.
Only the first 45 mins of the 6hr 10 mins journey is nothing special, once your passed Weiner Neustadt, the highlights keep on coming - the Semmeringbahn, the journey over the border into Slovenia and then through the Savinja and Sava River valleys.
Though you'll need to hope that your reserved seat is on the left side of the train, because it's that side that has the best of the views.
It's also worth planning an itinerary, so that you head south on this train, northbound it departs Ljubljana at 15:45, so in that direction it travels over the Semmeringbahn in darkness.
Because this daily train, which conveys a restaurant car, departs Zagreb Glavni kolodvor station at 07:25 - you'll get to experience the best of this stunning journey when heading north.
All of the scenic wonders, which earned it a place on our list of Europe's Most Epic Express Train Journeys can only be appreciated in this direction, because they occur in the first five hours.
You will also be travelling across the beautiful Slovenian landscape in dusk or at darkness - and in winter, you'll also miss out on experiencing the Semmeringbahn as well.
Departing daily from Zurich at 08:40, it is the only daytime train that connects Switzerland to the resort towns in the Kitzbuhel Alps and to Graz - in the opposite direction it heads west from Graz to Switzerland at 09:45.
Like those trains between Zurich and Wien/Vienna this travels on the wonderfully scenic route through the Arlberg Pass, but unlike those trains it also follows a beautiful route for pretty much the remainder of its journey.
A special First Class observation car, of the type which the national Swiss rail operator SBB uses on some scenic routes in Switzerland is usually included within the formation of this train. Tickets won't cost any more than typical First Class seats and rail pass users won't have to make reservations, or pay any other supplement, to ride in it.
It's the prospect of five hours of Alpine scenery that led to a spot on the Europe's Most Epic Express Train Journeys list
A route so fabulous that if you will be using a rail pass, to travel between Zurich and Wien/Vienna it can be worth, taking this train between Zurich and Leoben and connecting there for trains to and from the Austrian capital.
Although when ShowMeTheJourney did just that, the train travelled through a storm, hence a lack of images for the part of the journey east of Innsbruck.
I wanted to share my passion for train travel and explain how anyone can take the fantastic journeys I have taken.
This is one of more than 100 train travel guides available on ShowMeTheJourney, which will make it easier to take the train journeys you want or need to make. As always, all images were captured on trips taken by ShowMeTheJourney.