Ferries run frequently across the Río de la Plata between Buenos Aires and the Uruguayan cities of Colonia and Montevideo. Buquebus operates direct services to both cities on large car-and-passenger ferries, which take three hours (round-trip tickets cost 202 pesos to Colonia and 525 pesos to Montevideo). The best-value service to Colonia are the Colonia Express catamarans, which take an hour or less. Full-price round-trip tickets cost 190 pesos, and there are often large off-peak discounts if you book online.
The two companies also sell packages that include bus tickets to La Paloma, Montevideo, and Punta del Este on services direct from Colonia's ferry terminal. You can order tickets by phone or online.
Buquebus leaves from a terminal at the northern end of Puerto Madero. The Colonia Express terminal is south of Puerto Madero on Avenida Pedro de Mendoza (the extension of Avenida Huergo) at 20 de Septiembre. It's best reached by taxi.
Buquebus (11/4316–6500. www.buquebus.com.)
Colonia Express (11/4317–4100 Ext. 6 English operator. www.coloniaexpress.com.)