Buses are the cheapest way to get around and run frequently along the main coastal road. Wave one down at any corner — they will stop. No air conditioning, but they go everywhere you need for a few pesos.
Taxis are plentiful, especially in the downtown area. Agree on a price before you get in — there are no meters. Short trips within the city centre should be inexpensive; rides to the airport or the Marina will cost more. If the first price sounds too high, negotiate or try another cab.
Walking is the best way to explore the Centro and Zona Romántica. The Malecón promenade connects the two, and most of the restaurants, shops, and sights are within easy walking distance of each other.
Water taxis depart from Los Muertos Pier to beaches south along the coast — Yelapa, Las Ánimas, and Quimixto — that are only accessible by boat. A great way to spend a day.