Safety in Mexico
Possession of minor quantities of drugs is legal in Mexico, but it is safer to prevent drug use at all. The justice system tough.
Consult with locals to find out where to ride safely without a guide, and what places to avoid after sunset. They would be in a position to have the most reliable statistics.
Look out for riptides while you dive on the sea. They can be difficult to detect, but they can be very effective. Make sure to use sunscreen, and be careful of jellyfish.
If you're going by bus, don't put your bag in the storage space. This is a convenient way to rob your things. If you intend to take a taxi, contact the taxi service to ask for one instead of hailing one from the route. Rideshare services like Uber are available.