This is the 13285th most frequent Russian word.
морям
"Морям" means "to the seas" (dative plural of "море").
In this sentence, 'морям' is the dative plural form of 'море,' used to indicate motion toward multiple seas.
Мы приезжали к морям каждое лето.
We visited the seas every summer.
Here, 'морям' is the indirect object in the dative plural form, referring to the seas as recipients of the action.
Мы обещали помочь морям, очистив пляжи от мусора.
We promised to help the seas by cleaning garbage from the beaches.
In this example, 'морям' is used as the object of the preposition 'к' in its dative plural form to express affection towards the seas.