Marjan Public Beach is a quieter Muscat beach by day, with small coral reefs close enough to shore for novice snorkellers. You may see clownfish, parrotfish, sea cucumbers, and sometimes turtles or rays when the water is clear.
It gets livelier in the early evening, but the main reason to come is the simple combination of city beach and accessible reef. Bring your own snorkelling gear and be careful around the coral.