After swimming from Marazul to Playa Piskado, we'd usually swim partway back to Playa Forti, get out there, warm up a bit and then walk the short distance back to Marazul. If you want to snorkel under the cliffs at Marazul, but don't have access to that property, you could get in the water here at Playa Forti and swim out to the left.
