Whoops! Sorry about that! Thought you were posting a picture of what you saw! Rereading your post, you didn't actually get a picture of the eel, and do know exactly what a sandlance is. Maybe it was a wrymouth you saw, or a baby wolf eel?

http://www.burkemuseum.org/static/FishKey/crypt.html

http://wdfw.wa.gov/fishing/bottomfish/identification/wrymouths_eels/a_ocellatus.html