David Fleetham / Whitetip reef shark (Triaenodon obesus) cruises over a sandy bottom off the island of Maui, Hawaii.

Alex Mustard / Great hammerhead shark (Sphyrna mokarran) female cruises over the sand in shallow water. South Bimini, Bahamas. The Bahamas National Shark Sanctuary. Gulf Stream, West Atlantic Ocean.

Alex Mustard / Whitetip shark (Carcharhinus longimanus), accompanied by Pilotfish (Naucrates ductor), swims towards the camera as it cruises beneath the surface of the Red Sea, close to Little Brother Island. The Br...

Alex Mustard / Oceanic whitetip shark (Carcharhinus longimanus) is accompanied by pilotfish (Naucrates ductor) as it cruises beneath the surface of the Red Sea, close to Little Brother Island. The Brothers Islands N...

Rick Price / Le Lyrial expedition cruise ship sailing past icebergs, Cuverville Island, Antarctic Peninsula, Antarctica. December 2015.

Constantinos Petrinos / Cruise ship from 'Celebrity Cruises' anchored outside Mykonos Town since it is unable to enter the harbor due to its size. Mykonos Island, Cyclades, Aegean Sea, Mediterranean, Greece, August 2007.

Michael Hutchinson / Cruise ship and passengers in front of snow covered mountains, Paradise Bay, Antarctica, January.

Michael Hutchinson / Cruise ship passenger in outdoor hot tub, near mountains, Paradise Bay, Antarctica, January.

Michael Hutchinson / Cruise ship in front of snow covered mountains, Paradise Bay, Antarctica, January.

Alex Mustard / Oceanic whitetip shark (Carcharhinus longimanus) accompanied by pilotfish (Naucrates ductor) as it cruises beneath the surface of the Red Sea in the late afternoon, close to Little Brother Island. The...

Alex Mustard / Oceanic whitetip shark (Carcharhinus longimanus) accompanied by pilotfish (Naucrates ductor) as it cruises beneath the surface of the Red Sea, close to Little Brother Island. A rainbow runner (Elagati...