Through your snorkel mask you scan the gently swaying tentacles of a sea anemone. You see a fiery orange head poke out into the clear, warm water — a clownfish. You remember your classroom lesson about symbiosis, a kind of cooperation between species that the anemone and the clownfish perfectly exemplify. It is yet another hands-on lesson in marine biology here below the surface of Fiji’s waters, home to the largest variety of fish and coral anywhere in the world.