The inland waters around Cancun and Cozumel are popular boating destinations. As with any Caribbean destination, hurricanes can be a threat during the Summer and Fall. Warm tropical waters with great diving and snorkeling, attract many boaters. All of the Pacific coast cities have boating facilities and marinas. Most of these destinations are related to fishing rather than cruising per se.
Conditions can vary greatly depending on weather and sheltered sites.
The Pacific waters along the Baja are a little cold, and wet suits are needed, but most areas on the Sea of Cortez and the Caribbean coast, have warm tropical waters. Diving charters are available in virtually all coastal cities, and these people can show you where the best sites are. Everyone should experience snorkeling on a tropical reef at least once in their lifetime. The waters around Mexico are relatively teaming with fish. As many North Americans are finding out, the fishing is not nearly as good as it used to be in Canadian and American waters.