Isla Mujeres is a 12km long island 25 minutes off the coast of Cancun and a beautiful chilled out place with fantastic beaches, loads of bars and restaurants and more 2-4-1 drink specials than you can poke a stick at (although incidentally they seem to have missed the point as they were always more than the price of one drink!), where people cruise around in golf carts.
We rented an apartment for four days there which was great to be able to unpack a little and have a kitchen to use. The beaches had the finest white sands, no waves and crystal blue water which made them perfect for lazing around in, although the waves did get slightly rougher after the first night we were there when there was a cracking tropical thunderstorm.
Hired a scooter one day on the island to check out swimming with dolphins (too pricey) and the turtle sanctuary, full of heaps of turtles at various ages that they look after, some of which are released back into the wild. Lesson for that day was when curious Chris found out that turtles actually have sharp teeth and aren't adverse to biting!
Very relaxing few days, with lots of swimming, eating and checking out the 2-4-1s.