This fort is built at the beginning of the 18th century to avoid the constant looting by English, French, Dutch, Eastern, White and African pirates. Later, it became military barracks and finally opened its doors as a museum. In addition to the imposing construction, you can admire different pieces from the Mayan culture and colonial times.
It is called the lake of seven colors because of the white sandy bottom that gives the effect of having so many shades of blue, as you can see in the above photo. This is a freshwater lake feed by underground cenotes, but it does look like the ocean.