noun
lifesaver; lifeguard
Refers to a person who rescues people from drowning, typically at a beach or pool. Also used for the lifesaving ring (life preserver) in some contexts, but the primary sense is the person.
夏の間、彼は海でライフセーバーとして働いている。
During the summer, he works as a lifeguard at the beach.
ライフセーバーが溺れている
The lifesaver rescued the drowning child.