The great naturalist Jacques Cousteau called this gulf between the Baja California peninsula and the Mexican coast “the world’s aquarium”, and he was right; every day brings new, jaw-dropping sights, from hundreds of dolphins around the ship to humpbacks tail-slapping and rays flipping across the water like pancakes. You  can get so close to the grey whales in Magdalena Bay that you can touch them, and there’s a chance to don a wetsuit  and swim with sea lions.

The small-ship cruise line Un-Cruise Adventures carries marine biologists and naturalists on every voyage to teach guests about the environment, and keeping a tally of your sightings is all part of the fun.

  •  From £3,935 per person, including flights, departing February 10, 2017 (book through Mundy Adventures, 020 7399 7630,