Huatulco is a region along the central Oaxacan coastline. It's a series of bays (also known as Bahias de Huatulco) centered around the town of La Crucecita. Here's an aerial view of La Crucecita. We flew in to Huatulco from Oaxaca City on Aero Tucan which operates 12-seat planes around southern Mexico. It's a scenic flight although it might be worth looking away if you're a skittish flier. We cleared the ridge of the Sierra Madre between Oaxaca and Crucecita by about 50m. I know that because I was sitting right behind the pilot and it's an open cockpit. (Just ignore the terrain warning indicator)
Once you arrive, Huatulco has a very nice airport which includes this fish plane. The fish plane may have been the number one thing our son wanted to see in Oaxaca. Mission accomplished. There are a handful of direct flights to the southern US from Huatulco as well as assorted Mexican destinations and all the major cities in the Canadian prairie provinces. Even if you don't fly to Huatulco, this will become apparent through the sheer number of people wandering around in Saskatchewan Roughrider jerseys.
The primary reason to come here is of course the beach, or rather the beaches. There are many of them and this one is Tangolunda Bay. The water here is as warm as any place we've ever been on the Pacific coast of the Americas (warmer than Vallarta, Costa Rica and Panama).
There are plenty of fish in the bay in terms of snorkeling. These (called 'chupa' by the locals) hang out in a few inches of water at the east end of Tangolunda Bay.
Here's basically the same picture from under the water. Hi fish. The beaches are flagged by lifeguards and they were always red for the four days we stayed there. We started to think that perhaps they only have red flags because there were some days (particularly mornings) that the water was tranquil and lovely. Snorkeling in the bay on most days was just fine.
There are plenty of crabs (most beaches have local divers cooking and selling them), plenty of oysters (again, fresh and for sale on many beaches) and other sea life. There are a couple of Pacific stingrays visible in this picture.
West of La Crucecita town is Huatulco National Park which stretches along the coast. You can drive in to the fringe areas on a road, or take a boat along the coast. If you take a boat, it's probably out of Santa Cruz port. There are a lot of tours and a lot of restaurants here but it's not too bad in terms of sales pressure. We saw a lot of people trying to sell us hats and sunglasses. Wearing a hat and sunglasses immediately removes you from the possible buyer list. There is a cruise port here. It is not frequently used but from what we heard, you don't want to be here if a ship is in town. You probably don't want to be in the National Park either. If you're staying in town, learn the docking schedule and hide on a beach somewhere when a ship is in.
The 'lighthouse' and mirador (viewpoint) for La Crucecita. It didn't really seem like the view would be all that great if you're traveling along the coast anyway (which we were). There are certain times of the year when whales are seen more frequently though and it's probably a great location for watching them.
This is Maguey Beach in the National Park. We have nothing good to say about it. There are no good reasons to come here. People do come here however for two reasons: first, it's the only beach in the park that you can drive to. Expect a parking hassle if you choose that route as restaurants fight for your money. The other reason is that you took a tour (any tour) really to anything else along the coast and they bring you here 'for lunch'. Not just here, probably they will try to funnel you to whatever restaurant they are affiliated with. Food prices are exorbitant and we didn't hear any particularly good (or even average) reviews. Our tour stopped here, we avoided the restaurant and went to the far end of the beach where it was relatively quiet. The bay would be quite pretty if it wasn't full of tour boats and diesel fumes. Also, litter from all the boats and tourists. Every other beach in the park is fantastic, if you can possibly avoid Maguey, do so.
Case in point: the unparalleled crescent of sand that is Riscalillo beach. This is actually in walking distance from Maguey if you follow a trail. (To be fair, we didn't try this, we were only told of the trail so we don't know how feasible it really is). The water gets deep here quickly from the beach and obviously there isn't the tiniest bit of shade unless you bring your own.
Playa la India is just a few bays further west. There are two distinct sandy curves of beach on this bay and a very nice reef area visible here as the darker blue. The sand is lovely, the water is lovely. It did actually get a little bit 'crowded' before we left here (in a non-Maguey sense). There were maybe five boats anchored around the bay.
The reef here has a lot of fish, starfish and eels. It is a shallow reef in parts so be wary if snorkeling. The best way to see the land portion of the National Park is probably still to take a boat and work your way inland as far as you are willing. On the bays we stopped at it was hot, dry, rocky and filled with unfriendly foliage. The water was much more attractive.