Black-banded Sea Krait (Laticauda semifasciata) has Black Bands or sometimes darker bands that are wider on the top of the snake. there is a lighter horseshoe band that goes around the top to the head. They are also sometimes called the Chinese Sea Krait. They are venomous.
The colors are less distinct on this Black-banded Sea Krait. The colors can go lighter too. The color may change depending on the environment too.
Full Black-banded Sea Krait. Notice the paddle tail on the bottom. I should mention that Sea Snakes do breath air and this one is going up to get some. they can hold their breath way longer than I can.