Hierve el Agua is a pair of petrified waterfall formations with shallow mineral pools you can soak in, so come prepared like you would for a short hike and a swim. Expect a 20 to 40 minute walk from the parking area over uneven, sometimes dusty trails, so wear sturdy shoes, bring plenty of water, sunscreen and cash for the modest entry fee and snacks. Arrive early to beat the heat and crowds and to get a good photo spot, and be cautious near the cliff edges and fragile rock formations. Facilities are minimal, vendors sell simple food and drinks but do not expect full services, and if you plan to swim bring a towel and a change of clothes. If you are driving, be ready for a rough access road; many visitors prefer a guided day trip from Oaxaca City for convenience.