Updated.
Do we want to borrow this from the greater mummy?
Greater mummies receive a +8 racial bonus on Hide, Listen, Move Silently, Search, Sense Motive, and Spot checks.
Skills: 5 at 19 ranks
Mummies have Hide, Listen, Move Silently, Spot
Giant crocs have Hide, Listen, Spot
Feats: 6
Mummies have Alertness, Great Fortitude, Toughness
Giant crocs have Alertness, Endurance, Skill Focus (Hide)
I agree with demiurge that the greater mummy's racial bonuses are excessive, although I would be OK with a +2 or a +4 racial bonus on some or all of those skills.
I was originally just going to give the same racial bonuses as a crocodile - +8 Swim and "*A crocodile gains a +4 racial bonus on Hide checks when in the water. Further, a crocodile can lie in the water with only its eyes and nostrils showing, gaining a +10 cover bonus on Hide checks."
They do have a crocodile's head, so presumably they can hide in the water with just their eyes showing just like a real croc.
Shall we max out Hide, Listen, Move Silently, Spot and divide the remaining points between Search and Sense Motive?
Hide 19, Listen 19, Move Silently 19, Search 10, Sense Motive 9, Spot 19.
Hmm, I think the Search and Sense Motive could do with being a bit higher. I think I'd transfer a few points from Listen, MS and Spot.
Hide 19, Listen 17, Move Silently 16, Search 13, Sense Motive 13, Spot 17.
That looks OK to me.
EDIT: Including size and ability adjustments that gives us the following, not including whatever greater mummy racial adds we decide to give it (if any).
Skills:Hide +16 [+20 in water, +30 mostly submerged], Listen +19, Move Silently +17, Search +14, Sense Motive +15, Spot +19
EDITED EDIT: Oh yes, demiurge's proposed feats look fine to me, although I'll probably tweak them slightly for my version.