It is a snake eel (Ophichthidae); the specific variety is of a Sharptail Eel
Latin name: "Myrichthys breviceps"
{formerly "Myrichthys acumiactus")
Its distinctive features are the large, diffuse & pale spots on the body, and small yellow spots on the head. Body color is usually grayish (as seen here), but can vary darker (olive to purplish-brown).
Generally 1-2.5 ft long (max 3ft); generally found in shallow water; sand/patch reefs.
Like many eels, it is typically a shy day hider - night forager.
For reference, the Goldspotted Eel (Myrichthys ocellatus) is similar in general appearance (it also is light in color and has large diffuse spots on body), but its colors differ noticeably: its body is generally tan (not gray) and its body's spots are "two tone": black with bright yellow centers.
-hh