undersea

The technician repaired the undersea fiber-optic cable that provides internet connection to the island.

(Chinese) 技术人员修理了为岛屿提供互联网连接的海底光缆。

A new species of glowing fish was discovered during a scientific exploration of an undersea volcano.

(Chinese) 在对一座海底火山进行科学考察期间，发现了一种新的发光鱼类。