General term for a small watercraft, often used in compounds like ボートレース (boat race) or 救命ボート (lifeboat).
I rode a boat on the lake.
rowboat; rowing boat
Specifically a small boat propelled by oars, as opposed to a motorboat or sailboat.
I rowed a boat on the park pond.
We rode a boat and had fun on the lake.
He rowed the boat powerfully.
The waves were so high that the boat nearly sank.
airboat