Every generation establishes a sense of what is normal based on what they remember having seen, and we tend to set our goals for conservation in much the same way. We think we must work to keep things as they are - or, at most, hope to see a few slightly bigger creatures and a few more corals.

But we are much too low in our expectations, and thankfully there are still some places that remind us to raise our sights. On the Silver Banks north of the Dominican Republic, it's still possible to sit in a boat surrounded by humpback whales. Divers can be followed about by enormous jewfish and continuously buzzed by sharks in southeast Cuba. There are beaches in Central America where over 10,000 turtles still come up to breed each year. Snappers gather to spawn off the coast of Belize in such numbers that whale sharks - the world's largest fish - come in schools to feed on the eggs in the plankton.

This is the environment we should be aiming towards restoring everywhere.