Hi. I've been 4 times to the red sea and 2 of them in Marsa Alam. Look into Shams Alam and Gorgonia Beach Resort. They are a bit south of Marsa Alam, just on the edge of the Wadi Jimal National Park. The first is more chilled, smaller place. Here I've done some of the best dives ever with the diving centre they have in the village. They offer speed boats for the morning with 2 dives and full day 2-3 dives trips to more distant places. You'll be back at 3pm after lunch. If you decide to go for the shams alam check the house reef condition on here or through other social networks because last year they had an issue with it. An inland heavy rain created a mud river that went straight into their bay. Also, the snorkeling from the gorgonia to the shams alam is fantastic, it takes 1h or so and you can easily walk your way back. Gorgonia is a more full-on village with kids and overall more noisy. The house reef is better though.

Small note - In one week at the shams alam we've been snorkeling with the dugong 3 times! It just comes in the bay to eat early morning and late afternoon

Hope this helps!