The Sea or the Water is an area of the sky in which many water-related, and few land-related, constellations occur. This may be because the Sun passed through this part of the sky during the rainy season.
Most of these constellations are named by Ptolemy:
Sometimes included are the ship Argo and Crater the Water Cup.
Some water-themed constellations are newer, so are not in this region. They include Hydrus, the lesser water snake; Volans, the flying fish; and Dorado, the swordfish.
References
Sea (astronomy) Wikipedia(Text) CC BY-SA