Scuba Diving in Nature's Aquarium
The Sea of Cortez
Big Stuff. Big. Huge.
Jacques Cousteau called the Sea of Cortez (or the Gulf of California, as it is also known) “Nature’s aquarium” for a good reason. It is a comparative youngster in sea terms, only about five million years old, and formed by the volcanic activity that is still continuing today. Originally, the peninsula was part of the land mass of North America. The San Andreas Fault runs right through the middle of the gulf, and hydrothermal vents, evidence of active volcanic activity, are found at remarkably shallow depths. The peninsula is still being pushed away from the mainland by about two inches a year. As with other bodies of water with a similar geography, the sea here is saltier than expected as there is not much dilution with the wider ocean, and evaporation takes its toll. This means you may need to add a pound or two to your weight belt before diving, so do a check dive first. The sea life here is exceptional, and boasts some of the richest varieties of marine mammals.
Home to pinnipeds and cetaceans
Californian sea lions are often seen and can provide huge entertainment as they shoot through the water with an agility that is breath-taking. They will sometimes come up to take a closer look at scuba divers, even tugging on your fins if you are lucky, although bear in mind they are wild animals with sharp teeth and hence, unpredictable. Several types of whale live in the gulf, including grey, sperm, humpback, minke, and fin, as well as the mighty blue whale. Although cetaceans can be seen all year around, December, January and February are probably the best time, particularly if you want to see the humpbacks and greys. They are attracted by the plankton-rich waters, home to some 6,000 species of fish, including manta rays and the biggest fish in the sea, the splendid whale shark. Where there are plankton eaters, there will be predators and there is always the outside chance of seeing a great white hunting for sea lions. However, these are rarely seen; when one was caught in 2012, it was so unusual a find, it made headlines. Hammerheads used to be abundant but their numbers have declined due to heavy fishing practices, moving out to more remote areas.
The little vaquita
The endangered vaquita
Before you return home, try to catch a glimpse of the world’s smallest and rarest porpoise, the tiny vaquita. It is about four foot long and is only found in the gulf, but unfortunately, it is critically endangered There may be as few as 200 individuals left, but between 40 to 80 of them are being killed each year as by-catch, so if you are lucky enough to see one, take a photo and wish it well. The Mexican government is trying to protect the wildlife by creating marine parks such as the California Biosphere Reserve, where gill nets and trawling are prohibited, which will hopefully allow time for numbers to build back up again. However, as gestation is ten to eleven months and produces only a single calf, it will take a considerable time for this little porpoise to be back to full strength.