Copious rainfall has endowed Costa Rica with an abundance of rivers, but surprisingly, there are very few lakes. Nearly all the country's rivers begin in the mountains, where many are frothy white water routes perfect for rafting and kayaking. Once those rivers flow into the lowlands, however, they become languid waterways, many of which are lined with verdant walls of vegetation. Those lowland rivers are excellent routes for trips in small boats, which allow passengers to observe some of the local flora and fauna. The seasonal lake of Cano Negro is also an excellent spot for wildlife watching, whereas larger Lake Arenal is a popular windsurfing spot. Lowland Rivers A trip down one of Costa Rica's lowland rivers, either in a small boat or rubber raft, can be an excellent way to observe some of the country's extraordinary wildlife. The trees that line most river banks may hold lounging iguanas, troops of monkeys and such birds as ospreys, anhingas, colorful kingfishers, several species of herons and tiny mangrove swallows. Boat trips are offered on such lowland rivers as the Sarapiqui, San Carlos and Rio Frio, in the Northern Zone, and the Tempisque, Bebedero and Corobici, in the Northwest. Caribbean Canals The most popular lowland waterway trip heads up the Caribbean Canals, which run along the Atlantic coast north from the port of Moin to the communities of Parismina, Tortuguero, and Barra del Colorado. Most travelers head to Tortuguero National Park, which protects an important sea turtle nesting beach and vast expanses of lowland rainforest and swampy yolillal palm forests. A trip down any stretch of the canals is a true jungle adventure, offering opportunities to spot such animals as crocodiles, three-toed sloths, oropendolas and boat billed herons. They also offer world-class fishing for tarpon, snook and other species. Lake Arenal Actually the reservoir for the country's most important hydroelectric project, Lake Arenal is a vast body of water surrounded by rolling hills that hold pastures and patches of forest. Towering over the lake's eastern end is the conical form of Arenal Volcano, which regularly erupts spewing streams of lava and great clouds of ash. Though everyone who drives around the lake is impressed by the scenery, Arenal is especially popular with fishermen and windsurfers. The anglers are drawn there by the guapote, or rainbow bass, a feisty fish that thrives in the lake's waters. The windsurfers gather at the western end of Lake Arenal, where strong and consistent winds making it one of the world's premier windsurfing spots. Caño Negro Caño Negro, a shallow, seasonal lake near the country's northern border, is a bird watchers paradise during the second half of the year, when great flocks of ducks, herons and other waterfowl gather there. Cano Negro has been designated a wetland of international importance under the RAMSAR convention. Representations of Caño negro on most maps are actually misleading, since they show the lake's extension at the height of the rainy season. Once the rains die down in December, the lake rapidly shrinks, and by February it disappears completely, and most of the waterfowl has moved onto the Rio Frio -- the river that Caño Negro drains into. The river trip on the Rio Frio, which is the most common way of reaching Caño Negro, is consequently often more nteresting that actually visiting the lake.