March Gītā: 2.70

āpūryamāṇam acala-pratiṣṭhaṁ
samudram āpaḥ praviśanti yadvat
tadvat kāmā yaṁ praviśanti sarve
sa śāntim āpnoti na kāma-kāmī

‘Just as rivers flow into the sea, which is never filled and remains steady and immovable, so all these desires flow into such a person. It is he who attains peace, not one who seeks to fulfil those desires.’
Bhagavad Gītā 2.70

Even wanting to be free from desires is a desire. It’s only logical to think that reaching  enlightenment or liberation means losing - or at least transcending - so much of what makes us human. In this verse the sea represents one who has attained liberation. Not changed or polluted by the desires that flow into them like a river. This requires seeing desire for what it is and not being led by it (rather than trying to extinguish it). Maritime imagery was also used a few verses before this one  where Krishna says that being led by the senses is like being blown out to sea in a boat (2:67). It’s powerful symbolism. We often associate the sea with peril but it’s worth noting here that the sea does not represent danger in either verse. It’s our lack of understanding that puts us at risk of being swept away. 

– Tom Norrington-Davies