To the OP with regard to this map, you can pretty clearly see "downtown". The road that cuts across the island leads, basically, right to the center of it.
The marina is right where Paradise Reef is. (Paraiso). If you look south, you'll see Palancar reef. Almost every shop is going to take you on a Palancar dive, sooner or later, probably sooner. It's kind of a "sweet spot" of Cozumel diving. There are 4 different Palancar sites.
Most shops, the shop I use now included, will get you from downtown to the marina if you meet at their shop. Cost is covered, of course. Deep Blue used to leave from downtown and pick-up anywhere south, but as of 2022 anyhow, they'll get you to the marina if you're staying downtown or anywhere north, or they will pick you up at your hotel dock anywhere south of "downtown".
Fwiw, Colombia, Punta Sur, Chun Chakaab, Maracaibo are far, far south, but are dived regularly by many shops. They're considered somewhat advanced dives.
Short story, no need to drive anywhere. Inquire with the shop about their procedure.