カイ, うみ, あ, あま, うな, うん, え, か, た, ひろ, ひろし, ぶ, まち, まま, み, め, わたる

sea, ocean

JLPT4 G2 S9 F200

As per # (dark) + water → dark *sea/ocean* → *lake*; *vast*; *dense assemblage of objects*.

[Full Kanji Etymology List]