Article Detail Longest rail tunnel in the world ? Answer: Seikan Tunnel (Japan - 53.9 Km) Similar Questions : 1. Which is smallest planet ? Answer: Mercury 2. Which is largest Creature in world ? Answer: Blue Whale 3. Which is the highest Plateau ? Answer: Pamir, Tibet 4. Which is the Densest populated State of India ? Answer: West Bengal 5. Which is largest Dome in India ? Answer: Gol Gumbaz (Karnataka) 6. What is the name of brightest star ? Answer: Sirius 7. Which is the highest dam in India ? Answer: Tehri Dam on Bhagirathi River in Uttarakhand (Height of 260 metres) Read more from - Longest and Largest