Scuba diving

Diving's back, and it's been given real depth, in both senses. The official Keys screenshot shows a full reef: coral heads, a sea turtle in the middle of the frame and a diver working along it.

An oxygen meter replaces the stamina bar

Reporting on the Extended Look describes an oxygen meter replacing the stamina bar while you're under. It's a small change to the screen, and it does a lot of work.

In Grand Theft Auto V, swimming underwater ran off the same stamina bar as sprinting, so the seabed was basically a timer. A proper air supply, with equipment that makes it last longer, turns depth into something you plan for. You stop holding your breath and start actually diving.

What's down there

So far that's reefs with live coral and fish, turtles and rays. Footage from the Extended Look also has a character swimming among rays, and dolphins show up at the surface elsewhere in the official material.

Game Informer's issue 382 cover story adds sharks. Kotaku's summary of it lists them among the more than 170 species Rockstar told the magazine about, next to reptiles, birds and land mammals. Nobody's said where they swim or whether they'll go for a diver, and that's the bit we'd want to know before going down.

Rockstar built an enormous amount of animal behaviour for Red Dead Redemption 2, and it's clearly kept the appetite. Underwater is one of the few places where the wildlife is the whole point, since there's nothing else to do down there.

The Keys have a real reef

The real Florida Keys sit next to the only living coral barrier reef in the continental United States, and that reef's the reason the diving industry there exists at all. So Rockstar putting reefs in the same place is the map borrowing something real again, instead of making something up.

There's also an obvious criminal use for a diving system in a game about smuggling by boat. Rockstar hasn't said a word about that.

Into the caves

The Extended Look includes a diver swimming through an underwater cave, with light falling through an opening above, rays gliding overhead and an oxygen-style bar in the corner of the screen. Reef diving was already in the screenshots, and this adds caves to it.

What isn't known

We don't know whether diving gear is bought, found or given to you. We also don't know whether there's anything on the seabed worth finding, which in earlier games meant wrecks and collectibles, or whether either character can dive. And we don't know whether sharks are a danger underwater or just something to look at.