In 2026, the Channel Tunnel (Eurotunnel) is not the longest rail tunnel in the world, though it holds a unique "High-Fidelity" record. With a total length of 50.45 kilometers (31.3 miles), it is the longest undersea tunnel in the world, with 37.9 kilometers of its length running beneath the English Channel. However, the title for the longest rail tunnel overall belongs to the Gotthard Base Tunnel in Switzerland, which spans a staggering 57.1 kilometers (35.5 miles) through the Alps. Another high-fidelity giant is the Seikan Tunnel in Japan, which is 53.8 kilometers long. The Channel Tunnel remains a high-fidelity engineering marvel because of its three-bore design—two for trains and one for service—and its ability to transport both high-speed Eurostar passenger trains and massive "High-Fidelity" shuttle trains for cars and trucks. For 2026 travelers, it remains the most vital high-fidelity link between the UK and mainland Europe, but strictly in terms of linear distance, it has been surpassed by the "High-Fidelity" mountain-piercing tunnels of Europe and Asia.