noun
wreck diving
Diving to explore sunken ships, aircraft, or other submerged structures. A niche recreational and technical diving activity.
彼は沈船ダイビングのライセンスを取った。
He got a license for wreck diving.
沈船ダイビングでは、船内に迷い込まないよう注意
In wreck diving, you need to be careful not to get lost inside the ship.