National parks in Baja are not like those in the US. Little infrastructure exists in the park, rather it is a way to protect and conserve the reef and its sea life.
Many fingers of the reef can be reached from shore beaches, allowing easy snorkeling and fish viewing. While a fee is not required to walk the beaches, snorkelers are expected (and required) to purchase a permit, in the form of a bracelet (like you wear at a concert or event) for about $5 USD. While enforcement is spotty, the park police will require you to get out of the water if you are spotted with out the permit.
Visiting in the winter months, usually finds high wind and reduced visibility. Even so, in sheltered bays you can still see 30 feet or so.
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