Hello again, fellow train enthusiasts! As a detective, I'm always on the lookout for new cases to solve, but when I need to take a break from the sleuthing, I love to hop on a train and travel through some of the world's most impressive tunnels. So, let's put on our conductor hats and take a look at the largest train tunnels in the world, and the trains that will take you through them.

First up, we have the Gotthard Base Tunnel in Switzerland. This engineering marvel spans over 35 miles and is considered the longest train tunnel in the world. To travel through this epic tunnel, you'll need to ride the high-speed trains of the Swiss Federal Railways. These trains travel between major cities in Switzerland, and as you zoom through the Gotthard Base Tunnel, you'll have plenty of time to take in the stunning Alpine scenery outside your window.

Next up, we have the Seikan Tunnel in Japan. This tunnel spans over 33 miles and is the longest undersea tunnel in the world, connecting the main island of Honshu to the northern island of Hokkaido. To travel through the Seikan Tunnel, you'll need to ride the Seikan Tunnel Trolleybus, which takes you from Honshu to Hokkaido and back. As you travel through the tunnel, you'll have the unique experience of traveling beneath the sea and witnessing the incredible engineering that made it all possible.

Moving on to another impressive tunnel, we have the Channel Tunnel, also known as the Eurotunnel. This tunnel connects the United Kingdom and France, spanning over 31 miles beneath the English Channel. To travel through the Channel Tunnel, you'll need to ride the Eurostar high-speed train, which connects London to Paris, Brussels, and other major European cities. As you travel through the tunnel, you'll feel like you're hurtling through the depths of the ocean, with nothing but the train tracks and the dark tunnel walls around you.

Another notable tunnel is the Lötschberg Base Tunnel in Switzerland. This tunnel spans over 21 miles and is one of the longest in the world. To travel through the Lötschberg Base Tunnel, you'll need to ride the high-speed trains of the Swiss Federal Railways once again. As you travel through the tunnel, you'll have stunning views of the Swiss Alps outside your window, making for an unforgettable train journey.

Last but not least, we have the Guadarrama Tunnel in Spain. This tunnel spans over 15 miles and is one of the largest in Europe. To travel through the Guadarrama Tunnel, you'll need to ride the high-speed trains of Spain's national railway company, Renfe. As you travel through the tunnel, you'll have stunning views of the Spanish countryside outside your window, making for a relaxing and scenic train journey.

So there you have it, folks - some of the largest train tunnels in the world, and the trains that will take you through them. Whether you're a thrill-seeker or an engineering enthusiast, traveling through these tunnels is sure to be a once-in-a-lifetime experience. And who knows - maybe you'll even solve a mystery or two along the way, just like yours truly, Detective Pux. Happy travels!