Yes, sea is a Scrabble word!
...and is worth 3 points in Scrabble, and 3 points in Words with Friends
sea
Noun
1. A division of an ocean or a large body of salt water partially enclosed by land
2. Anything apparently limitless in quantity or volume
3. Turbulent water with swells of considerable size
What Scrabble words can I make with the letters in sea?
3 Letter Words
2 Letter Words