Here’s a scene that plays out on almost every trip. Two divers surface from the same dive. One is buzzing about the sea lions and the school of jacks that swept through. The other is quietly grinning about a nudibranch the size of a grain of rice, in colours that shouldn’t exist in nature, that they spent ten minutes photographing on a single rock. Same dive. Completely different trip.
The Sea of Cortez is famous for its big stuff, and rightly so. But slow down, get your eyes in, and there’s a whole other world down there — a macro world of nudibranchs and tiny critters that most divers swim straight past. Here’s how to find it, and why it might just become your favourite kind of diving.
What “macro” diving actually means
Macro diving is simply diving for the small stuff. Instead of scanning the blue water for something large to swim by, you slow right down and work a small patch of reef, looking for the tiny animals living on it. Think of it as the difference between watching for whales and turning over a rock pool as a kid — both are fun, but they use completely different parts of your attention.
Once you learn to see at that scale, a “boring” patch of reef turns out to be absolutely crawling with life. The reef never got less interesting. You just weren’t looking closely enough.
The stars of the show: nudibranchs
If macro diving has a mascot, it’s the nudibranch. These are sea slugs, which sounds deeply unglamorous until you actually see one. They come in colours and patterns so vivid and strange they look designed by someone showing off — electric blues, oranges, purples, frills and horns and spots. There are a huge number of species, and the Sea of Cortez has a rich variety of them.
Part of what makes them such a satisfying subject is that they don’t flee. Nudibranchs move at, well, a snail’s pace, so once you find one you can take your time, watch it graze, and photograph it properly without chasing anything. For anyone learning underwater photography, they’re the perfect patient model. We love them enough to keep a running gallery of the nudibranchs our divers turn up.
Beyond the nudibranchs
Once you’re diving slow and looking close, the nudibranchs are just the beginning. The macro cast of the Sea of Cortez is deep.
There are tiny shrimp tucked into anemones and among coral, some almost transparent. Blennies and gobies peer out of holes and bolt back the instant you get close. Juvenile fish, in their odd temporary colours, hide in the structure. Eels thread through the rocks. Octopus — masters of disguise — sit in plain sight until a shift of texture gives them away, and then you can’t un-see them. Crabs, hermit crabs and other crustaceans work the reef constantly. And there’s a whole category of “what on earth is that?” creatures that send people back to the boat scrolling through ID guides.
The reward of macro is that no two dives turn up quite the same list. It’s a treasure hunt where the reef restocks itself.
How to actually see the small stuff
Macro diving is a skill, and it’s a learnable one. A few things make the difference between swimming over a rich reef and actually seeing it.
Slow down — more than you think. The single biggest change. Most divers move far too fast to notice anything small. Cut your pace to a crawl, then cut it again. Pick a small area and really look at it rather than covering ground. The divers who see the most are almost always the ones moving the least.
Nail your buoyancy. To hover close to the reef and study a patch of it without crashing into it or kicking up silt, you need genuinely good buoyancy and trim. Macro diving and good buoyancy go hand in hand — and happily, practising one improves the other. If your buoyancy is still a work in progress, macro diving is a great, low-pressure way to sharpen it.
Look for the odd one out. Your eyes learn to spot the thing that doesn’t fit — a shape, a colour, a texture that’s slightly wrong for the background. That “off” patch is often an animal. It takes a few dives, and then something clicks and you start seeing them everywhere.
Let a guide show you the first few. Spotters who dive a site regularly know where the resident critters live and what to look for. Diving with one of our guides is genuinely the fastest way to train your eye — once someone points out your first three nudibranchs, you start finding the fourth yourself.
A note on doing it respectfully
The macro world is fragile, and getting close to it means getting close to the reef. So the usual rules matter double. Don’t touch, poke or move animals to get a better angle — a nudibranch isn’t a prop. Keep your buoyancy tight so you’re not resting on or fanning the reef. And resist the urge to crowd a subject for a photo. The reef stays this rich precisely because divers tread lightly on it.
Come dive slow with us
If the idea of spending a dive hunting for thumbnail-sized animals in impossible colours appeals to you, the Sea of Cortez is a wonderful place to do it — and San Carlos puts you right on top of it. Take a look at the diving we offer, browse our photo gallery to see what turns up down there, and let us know if macro is your thing so we can point you at the right sites and the right guide.
Come for the sea lions. Stay for the sea slugs. We’re only half joking.