I did this quest until i got the map. I dont understand where the map is pointing me ive looked but I cant find the treasure. If anyone can help id be greatful.

"Make itself visible when you get near."

It may also be glitching where you can't 'see' the treasure. According to him it was stashed from an Imperial Galleon.

I was talking about after freeing the dremora and finding the treasure. I dont know where the treasure is.

http://www.uesp.net/maps/srmap/srmap.shtml?centeron=Velehk+Sain%27s+Locker.

"located west-northwest of Winterhold, and north of Saarthal, on an island with a statue of Talos"