China unveiled new dragon-themed drillers that it hopes will build the world's 'longest undersea high-speed railway tunnel'

• China just showed off its second dragon-themed tunneller, which it said will drill an undersea railway.
• It's touted by China as the world's longest undersea high-speed railway tunnel.
• But that's likely a matter for debate. A high-speed tunnel in Japan has a longer underwater section.

China's state-run railway giant on Monday revealed the second of its dragon-themed tunnel-boring machines for what it says is the longest undersea rail channel in the world.