Visit at least a few of these archaeological sites - Chichen Itza (New wonder of the world), Tulum, Coba, Monte Alban, Calakmul, Palenque, etc.; also cave paintings in Baja California
Snorkelling -
Baja California, Cancun,
Cozumel, Isla Mujeres, etc.
Scuba diving - Baja California, Cancun, Cozumel, Isla Mujeres,
Visit Acapulco, Cabo San Lucas etc.
Whale Watching - Baja California
Visit a Volcano - Mexico, Toluca etc.
Take a ride on the Copper Canyon Railway
Go for a horseback ride in the Sierra Madre mountains
Surfing - Baja California, Vallarta, Oaxaca
Sea Kayaking - Baja California