From the port of Tigre, in the northern suburbs of Buenos Aires, a comfortable catamaran winds through the forests in the myriad channels of the Rmo Parana delta before finally reaching the fortress island and former penal colony of Martin Garcia, a bedrock island just a short distance from the Uruguayan shoreline. Though its area is only about 500 acres, its carless roads and woodsy hiking trails, coupled with historic monuments, make for an ideal day trip from Argentina's capital. Of particular interest are the former naval barracks and well-preserved turn-of-the-century buildings like the still-functioning bakery and the ornate cinema.