Final answer:
The sentence 'I hear their plea.' in the third stanza of 'Ocean's Gift' means that the author is listening to the request or appeal made by someone or something.
Step-by-step explanation:
The sentence 'I hear their plea.' in the third stanza of 'Ocean's Gift' means that the author is listening to the request or appeal made by someone or something. In this case, the author is personifying the ocean and describing it as crying out or making a plea. The use of the word 'plea' suggests that the ocean is trying to communicate or express something to the speaker.