Jeff Rotman / Snorkelers interacting with wild Bottlenose Dolphin (Tursiops truncatus), Nuweiba, Egypt, Red Sea. Model released Model released.

Juergen Freund / Quicksilver Pontoon with tourists snorkeling watching fish split-level, Great Barrier Reef, Queensland, Australia 2006

Doug Perrine / Reef manta rays (Manta alfredi formerly Manta birostris) filter feeding on plankton, with snorkelers and scuba divers in background, Hanifaru Bay, Hanifaru Lagoon, Baa Atoll, Maldives, Indian Ocean, O...

Juergen Freund / Giant manta ray (Manta birostris) at a cleaning station with snorkelers. North Raja Ampat, West Papua, Indonesia.

Patricio Robles Gil / Snorkelers, Balandra Bay, Baja California, Mexico, September

Fred Bavendam / Whale Shark (Rhincodon typus) swimming along with two snorkelers, Ningaloo Reef, Australia

Juergen Freund / Two snorkelers at Langkayan Island, Sabah, Borneo, Malaysia

Juergen Freund / Aerial view of the Great Barrier Reef with tourist dive boats. Agincourt Reefs, off Port Douglas, Australia

Juergen Freund / Quicksilver Pontoon with tourists preparing to snorkel, Great Barrier Reef, Queensland, Australia 2006

Juergen Freund / People snorkeling from Quicksilver Pontoon, Great Barrier Reef, Queensland, Australia 2006

Juergen Freund / People snorkeling from Quicksilver Pontoon, Great Barrier Reef, Queensland, Australia 2006

Juergen Freund / Quicksilver Pontoon with tourists snorkeling watching fish split-level, Great Barrier Reef, Queensland, Australia 2006

Doug Perrine / Aerial view of boats and snorkelers, Looe Key Reef, Florida Keys National Marine Sanctuary, USA, showing spur and groove coral formations.

Doug Perrine / Pleasure boat and snorkelers, Molasses Reef, Key Largo National Marine Sanctuary, Florida, USA

Doug Perrine / Snorkelers and bait fish at 'Treasure Caves', Norman Is, British Virgin Islands, Caribbean

Mike Parry / Dugong (Dugong dugon) surrounded by snorkelers, Lamen Bay, Epi Island, Vanuatu

Fred Bavendam / West Indian Manatee (Trichechus manatus) pair with snorkelers in Kings Bay, Crystal River, Florida

Juergen Freund / Whale shark {Rhincodon typus} + snorkelers. Donsol, Philippines

Daniel Gomez / Snorkelers in river, Rio da Prata, Bonito, Brazil, South America

Roberto Rinaldi / Divers on the surface with snorkellers in the background, Maldives.

Hiroya Minakuchi / Bottlenose Dolphin (Tursiops truncatus) observed by three snorkelers, Belize

Jeff Rotman / Snorkelers at coral reef Red Sea Model released.