This is the 5484th most frequent Japanese word.
うみ
Sea; ocean.
In this sentence, 'うみ' (海) refers to the sea as a body of water where one can swim and enjoy activities.
海で泳ぐのが好きです。
I like swimming in the sea.
Here, 'うみ' as '海' signifies the marine environment, a habitat where marine species exist.
彼は海の生物について研究しています。
He is doing research on marine organisms.
This usage of 'うみ' (海) identifies a geographical area located near a vast body of water, emphasizing the physical location.