You will be right across the street from The Thirsty Cougar. Good food, great ceviche, and great drinks. It's a little touristy, but consistently good never the less. Lobstershack will be next door. They do their take on a lobster roll and it's pretty good too. Dump the slaw on it. Guidos is a white table cloth restaurant a couple of blocks North. Pizza is good, best scallops I've ever had. Cheap by white table cloth US standards, but more expensive by Cozumel standards. Burrito Gordito for a cheap great lunch, there is a bakery next to Burrito Gordito that is amazing....and cheap. It's a few blocks North, turn right at Ron Jon, go past Blue Magic Scuba, and it's on the corner. If you like Amber beer, there is a beer I can't get in the US called Bohemia Obscura....best beer I've ever had.
Your breakfast will be at the buffet at Casa Mexicana about 2 blocks south. It's the best breakfast buffet on the island. If I remember correcty, Aldora leaves their pier at 7:30, breakfast starts at 7:00. Coffee and fruit is usually out a little earlier. We had plenty of time for a trip to the buffet, maybe something quick for seconds, lots of juice and water, then walk to the Aldora pier about 1/2 a block away. We were always on time, but it didn't matter, lots of people were either late at the Aldora pier or at hotel pickups. No one got left and we had great dives.
Aldora does their SI at a beach club that charges for food, drinks, and padded beach lounge chairs. There is bottled water on the boat and chairs under the shelters and unpadded lounge chairs are free, as well as the facilities. Bathrooms and showers are clean. It was about $10 us for a Coke and a fruit plate. I believe that Casa Mexicana will pack you a light lunch off the breakfast buffet if you ask. I would suggest diving Nitrox, the insane bottom times will create the need for a nitrogen nap afterwards. Sometimes those naps were extended. If you want to explore the Island after a dive, Nitrox should make it more enjoyable.
Take a cab, or walk, to Mega when you get there. It's a huge supermarket, kind of like a Mega-Walmart that sells appliances, scooters, etc. stock up on water and snacks for the room. Take a backpack and don't forget to check it in at the front of the store when you come up the escalator like ramp. Yucatan bananas are like crack....be warned. It's interesting to see the products and their bakery is good as well.
You will be amazed at your bottom times. Our last dive was shallow and it was almost 90 minutes. If you pay cash for the discount at Aldora, bring exact change because they had to go down the street to get change when we paid. Also.....whether you have done a night dive before or not....DO A NIGHT DIVE!!! even if you have to skip a meal to fit it in the budget, it's worth it!
Safe travels,
Jay