Leviathan (Manhwa)

Leviathan is a webtoon by Lee Gyuntak and Noh Miyoung.

Summary
In the world where the sea level has risen, the water has already covers the continents. In the world where dry land cannot be found anymore, Bota's family lives in a small boat and wanders the ocean and scavenges for food and parts from under water cities. Below the surface lurks sea monsters that hunt for food and that includes people. After a near fatal encounter with the monsters, Bota meets the mysterious Kana.