When I first visited this restaurant it was called Paella Club. It has since changed its name. However, the food and the menu remain the same.
I have visited the Altamar Restaurante Español on three separate occasions. The owners are brothers, and relatives, that have immigrated from Spain. They brought their local specialties to Cancun to share in the dining market.
The reaturant is listed in the Cancun guide as a seafood restaurant. While there is seafood on the menu, I recommend any of the paellas that they make. They even have a seafood version. The flavors of this Spanish dish are distinctly different from those that many consider Mexican food. The blend of saffron mixed in the rice is quite unique to Spanish food.
The service is excellent, especially if you speak with the waiters about their experiences in Spain. There is a xylophone player who will play your requests, as well as many other songs that he knows. He has a large variety of songs to play. Ask for a romantic Mexican or Spanish song. You will certainly enjoy the experience.
This is one of my favorite places to visit when in Cancun.