Caribbean:

The vents are also known as "black smokers"

Cayman vents are world's hottest

The world's deepest known volcanic vents are also the hottest, a UK-led expedition has indicated.

The seafloor vents are located 5km below the surface of the Caribbean, in the Cayman Trough. The researchers say the structures are shooting jets of mineral-rich water more than a kilometre into the ocean above.

The vents' features suggest the water is warmer than 450C - hot enough to melt lead.