Mahahual
"Two hours by collectivo to get here, 180 pesos a night, nobody else on the reef at seven in the morning. Some things still work."
The collectivo from Chetumal to Mahahual takes about two hours on a road that goes through a long passage of flat jungle with nothing much to look at and then, without much warning, arrives at a fork where you turn toward the coast and the vegetation opens up and you can suddenly smell the sea. The town at the end of the road is small enough that you have essentially walked its length before you have made any decisions about where you are staying.
I had come from Felipe Carrillo Puerto via Chetumal — a full day of second-class buses and collectivos through the southern Quintana Roo lowlands — and I arrived in Mahahual late enough that the light was already going gold over the water. The Caribbean at this part of the coast is the specific shade of turquoise-green that you have seen in photographs and assumed was a filter. It is not a filter. The shallow water over the sand flats between the beach and the reef genuinely looks like that.
The Malecón and the Town
Mahahual has a malecón — a seafront promenade — that runs for perhaps a kilometer along the beach, lined with small restaurants, dive shops, guesthouses, and the kind of low-key commercial strip that caters to budget travelers without performing the idea of budget travel for them. The restaurants serve fish tacos and ceviche and whatever came off the boat. The dive shops are staffed by people who know the reef very well.
The guesthouse I found — two blocks back from the malecón, run by a woman named Carmen who gave me a room with a hammock on a small terrace — cost 180 pesos for a night that included a fan, a padlock for the door, and a strong suggestion that I be back before midnight because she locked the gate. I was back before midnight. The hammock was excellent.
In the mornings before the cruise ships arrive — and I will explain the cruise ships in a moment — Mahahual is very quiet. The malecón has a few fishermen working at the far end. The restaurants are setting up their chairs. The pelicans are active above the water in the way pelicans are when they are confident no one is watching.

The Reef
The Costa Maya reef runs just offshore from Mahahual — part of the Mesoamerican Barrier Reef, which is the second largest coral reef system in the world after the Great Barrier Reef. The snorkeling here is accessible directly from the beach: you swim out past the sand flat, cross a band of seagrass, and drop over the edge of the reef into fifteen or twenty feet of water filled with coral formations, reef fish, and the blue that exists at depth over a living coral reef.
I went in at seven in the morning with fins and a mask I had borrowed from the dive shop for a fee that I cannot now remember but know was trivial. There was no one else in the water. The reef was not pristine — no reef this close to a cruise ship port is pristine — but it was healthy enough to be impressive. I saw a small barracuda, a school of blue tangs, several parrotfish doing the thing parrotfish do to coral, and a large sea turtle that looked at me with the specific expression of complete indifference that sea turtles have, turned, and went somewhere else.
I was in the water for ninety minutes without intending to be. The sun was getting high enough to be warm on the back of my neck by the time I got out.
The Cruise Ship Parenthesis
Around ten in the morning on the day after I arrived, the cruise ship appeared. It anchored offshore near the purpose-built cruise pier several kilometers from the town center, and then it sent approximately a thousand people to Mahahual by tender. They arrived on the malecón in a flood, filling the restaurants and the souvenir shops and the beach chairs that had been set up specifically for them, and then — and this is the particular quality of the cruise ship phenomenon — they were gone by three in the afternoon.

The malecón transformed twice in a single day: from quiet fishing village to Caribbean tourist strip and back again. By four o’clock the restaurants were quiet and the souvenir vendors were packing up and the pelicans were back. I ate fish tacos at the counter of a small place near the water and watched the ship on the horizon, lights coming on as the evening arrived.
Mahahual is three hours from Chetumal by collectivo and has no direct bus connection to Tulum or Cancún. This is not a bug. The difficulty of getting there is the mechanism by which the town remains what it is.