Everyone on Cozumel lives in San Miguel. It is the island's only town, strung along the leeward waterfront, and essentially every road, ferry, taxi and dive boat starts or ends here. For cruise passengers it is a place they walk through for an hour; for anyone staying on the island it is where the evenings happen. Those two versions of the town barely overlap.
The waterfront is the malecón, a broad seafront promenade running north from Punta Langosta past the ferry terminal and the main square, with the sea on one side and the town on the other. It is flat, walkable, busy in the afternoon and genuinely pleasant after dark. Behind it, the Plaza del Sol — the main square — is the town's centre of gravity: a bandstand, benches, trees, ice cream, families, and on Sunday evenings a municipal concert that is aimed squarely at Cozumeleños rather than at visitors. Turning up to that is the best hour a visitor can spend in San Miguel.
The most useful thing to understand is the gradient. Everything within a block or two of the water is priced and stocked for people who will be back on a ship by six: jewellery, tequila, silver, branded shops, restaurants with English-first menus and a host outside. Walk three or four blocks inland, past Avenida 10, past Avenida 20, out to Avenida 30, and the menus change language, the prices roughly halve, and the clientele becomes local. Nothing dramatic happens at any particular corner. It just gets steadily more like a Mexican town and less like a port.
Pay in pesos. Dollars are accepted almost everywhere, at a rate quietly worse than any bank or ATM would give you, and the pier-adjacent shops are the worst offenders. Taxis have no meters and run on posted zone tariffs — agree the fare before you get in.
The town's other trick is that it empties. When the last ship sails in the late afternoon, San Miguel exhales, tables free up, and the malecón becomes a place people walk their dogs.