Trying to stay above water, that's why we shun the navy
He’s trying to stay above water as in survive in a society that makes it easy to drown in the media as well as sets us up to fail. .
In the Navy, they perform many underwater operations. He refers to “above water” as surviving in today’s society. Being “under water” would be being in massive debt, being in jail, or even dead.
Also, the military is known to notoriously recruit in the ghetto’s as those lives have a lower value & are most probable to join since its youth are oppressed. Therefore, Kendrick is stating he & his peers shun (disapprove of) the navy since they are trying to remain sane. J. Cole always talks about this dynamic, so it is relevant that it is incorporated in this song.
This is a similar line to one in the beginning of Big Sean’s “Wait for Me” featuring Lupe Fiasco:
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