I shore dive there, both solo (only to about 22' where the main reef bottoms) and sometimes with friends (for an easy afternoon dive). But, the snorkeling is so good there's really no need (unless one can't get down to say 10' snorkeling/freediving).
There is a second patch type outer reef (pretty flat in topography) that gets down to lower 30'-something if I remember correct, just follow the reef edge of main shore reef until it makes the turn to the north and then swim out and slightly north, you can't miss the first of the two outer reefs.
But, there's nothing at Ulua that I've seen diving that I haven't also seen snorkeling - from one inch sized frogfish and leaf scorpion fish and nudis, to larger animals like manta and eagle rays.