(idiomatic) godsend, lifesaver

outside of a 船 – boat (船), spaceship (宇宙船), etc.

Suspicious seacraft. The DPRK (North Korea) especially has a habit of iilegally trespassing into Japanese waters.

tour boat

riptide, rip current, offshore current - a strong surface flow of water returning seaward from near the shore.

Synonym of 黄昏 (tasogare, “dusk; twilight”) / Synonym of 黄昏時 (tasogaredoki, “dusk; twilight”)

extravehicular activity

engage in an extravehicular activity

catamaran

a shipworm