Sea is the body of water that Nephi and his company called Irreantum. They “beheld the sea, which we called Irreantum, which, being interpreted, is many waters,” and pitched their tents “by the seashore” (1 Nephi 17:5-6).
A speaker asks, “is my hand shortened at all that it cannot redeem,” then says, “at my rebuke I dry up the sea” (2 Nephi 7:2). Jacob says that in the name of Jesus, “the waves of the sea” obey (Jacob 4:6).