This is one of the rays most commonly seen by beginner divers - it's rather ubiquitous on tropical reefs throughout the pacific. Often described as a stingray (and indeed you can clearly see a sting on this one), I prefer to see it described as a ribbon tail or fantail ray. This at least acknowledges that these round disked rays with their blotched tails are different to the pointy snouted Dasyatis rays or the whiptail rays of the genus Himantura
The species belongs in the same genus as the spectacular blue-spotted ribbontail ray (also beloved of divers) and its a pleasure to see them. To my mind the lack of a pointed nose makes the ribbontails seem friendlier looking somehow. They look like giant velvety doillies dotting the seafloor. Lovely critters which will tolerate very close approaches if divers are slow and steady.
Occasionally one will find huge numbers of these together and certain sites are well known for this (often these sights are more famous for accompanying schools of ray-loving hammerheads or for the chance of seeing silvertip sharks). In fact a photographer acquaintance of mine was diving one of these once when a pod of Orca turned up and started feasting on the rays! This one remained unmolested by anything so exciting during my time with it (to my minor disappointment).
Notwithstanding the above, there is another reason I'm particularly fond of this species. My best friend's 3 year old daughter has a fluffy stuffed marbled ribbontail ray that her uncle tai brought back from a trip somewhere or other which seems to be her favourite toy of all and which is produced with a great amount of flamboyance and delight and the words "here's my stingray you got me" whenever I visit (she also has a fluffy Cyclura iguana and a fluffy black bear - because I give awesome (and zoologically accurate) children's toys).
