Here is a view of the Marsa Shagra site. The shallow reef plateaus to the north and south are off limits, in other words no snorkeling or even walking in the water along the beach is allowed here to protect its function as a fish nursery. I have no idea if a similar laudable rule is enforced at Abu Dabab. The sandy bit in the middle where the zodiacs are moored could be nice for kids. Divers enter the water here, or are are ferried out and/or back by zodiac.
I've seen juvenile whitetip reef sharks in a cave on the southern side, huge moray eels hunting and fighting on night dives right under the jetty, dolphins on the outside to the north and the reef is just vibrant with life. Mind you, as the sun moves to the west during the day the reef moves into the shadow.
Abu Dabab on the other hand is a bay with a long sandy beach, more suited to your regular sun seeking tourist crowd.
In front of the beach a sandy bottom with fields of sea grass slopes gently downwards. This is where you can observe giant turtles, guitar sharks and -if lucky- Dennis the dugong. Also squid and cuttlefish, juveniles of several reef fish species and last week some friends of mine saw a whale shark here. Lucky buggers. I believe someone on
this forum recently photographed a mimic octopus on the same spot.
The southern side is shallow, and the sunlight reflects off the sandy bottom which I consider a favorable condition for photography. The northern side (where you can see the liveaboards are moored, though I believe they are now banned) goes deeper quickly. In the shallow end near the shore I have often experienced bad visibility at the end of the day.
FWIW,
Art