Article Detail Longest rail tunnel in the world ? Answer: Seikan Tunnel (Japan - 53.9 Km) Similar Questions : 1. Which is longest river of South India ? Answer: Godavari 2. Which is the biggest museum in the world ? Answer: British Museum, London 3. Which is the largest Mosque in World ? Answer: Masjid al Haram (Saudi Arabia) 4. Which is the largest desert in India ? Answer: Thar (Rajasthan) 5. What is the name of tallest Animal ? Answer: Giraffe 6. Which is the lightest gas ? Answer: Hydrogen 7. Longest rail tunnel in the world ? Answer: Seikan Tunnel (Japan - 53.9 Km) Read more from - Longest and Largest