Versus the Money Bar at Dzul-Ha, kilometre 6.5. Dzul-Ha has the better and more varied reef and the shorter transfer, and it has historically charged nothing to walk in. Sky Reef has more structure, an all-inclusive option if you want one, and slightly fewer excursion groups landing on top of you. If you only do one shore snorkel on Cozumel, do Dzul-Ha. If you want a beach club that happens to have a reef, come here.
Versus Playa Corona, a kilometre or so north. Playa Corona is simpler, cheaper and family-run, with a palapa restaurant and very little else. Sky Reef is the more comfortable version of the same idea.
Versus Mr Sanchos or Paradise Beach at kilometre 14 to 15. Those are sand, pools, buffets, open bars and inflatables, with no snorkelling worth the name because the bottom in front of them is sand and seagrass. Choose by what you want to look at. Sand and a drink, go south. Fish, stay here.
Versus a boat trip. Nothing on this shoreline matches Palancar Gardens or the El Cielo sandbar. A shore reef is shallower, smaller and more worn because thousands of people swim over it every week. What it gives you instead is no schedule, no boat and no marine park wristband.