The water's cold, but the views gorgeous, paddling along Mount Desert Island, home of Acadia National Park/Rebecca Latson

Spring has set in throughout the country, perennials are reappearing, if they haven't already started to bloom, and summer vacation for some could be just weeks away. If you need some suggestions on where to float in the National Park System, we have them.

Acadia National Park, Maine. Paddling might not immediately come to mind when you start thinking of an Acadian vacation, but there are some pretty good opportunities on this island along the coast of Maine. There are a number of lakes where you can canoe or kayak, and the Atlantic waters rimming Mount Desert Island are wonderful for paddling. Outfitters stand ready to guide you into these waters, and some offer multi-day island-hopping trips.

Grand Teton National Park, Wyoming. The Snake River is the main aqueous attraction here, but something a tad more subtle is often more appreciated. String and Leigh lakes are both well-known for their relatively warmer waters. String Lake is the warmer of the two, thanks to its relatively shallow (nothing deeper than 10 feet here) water. The big lake, Jackson, has waters that can be tolerated, but not everyone likes the power boats that rip it up.

Glen Canyon National Recreation Area, Utah. If you can't find the water here, your eyes must be closed. This NRA was formed around that reservoir-known-as-Lake Powell. You can houseboat here, sea kayak, canoe, or hike with a water-side campsite every night. If you head here, take the time to explore the watery backcountry, escape the crowds and find a secluded side canyon, preferably one with some hanging gardens. For some good suggestions on where to head, take a look at this page.

Little River Canyon National Preserve, Alabama. OK, getting wet doesn't always mean by swimming. Little River Canyon might only cover roughly 14,000 acres atop Lookout Mountain in northern Alabama, but the river packs a lot of wallop for experienced kayakers. Said to have carved the deepest canyon (roughly 600 feet) in the Southeast, and offering the cleanest water in the region, the Little River boasts rapids ranging from Class III to Class VI that lure paddlers when spring runoff hits. During the summer there are plenty of sand-bottomed pools to cool off in.

Grand Canyon National Park, Arizona. The "big Kahuna" when it comes to floating in the National Park System, at least within the Lower 48 states. You can lose yourself here for two or three weeks, easily, floating from Lee's Ferry all the way down to Diamond Creek. You can do it yourself, or, sign on with a commercial outfitter and let them do the hard work of guiding you safely through rapids and cooking meals.

The Green River offers an above-ground adventure in Mammoth Cave National Park/NPS

Mammoth Cave National Park, Kentucky. For easily paddling suited for the entire family, with some lovely forestlands to drift through, the Green and Nolin rivers through the above-ground portion of Mammoth Cave is an easy choice. There are a good number of canoe liveries that will rent you a canoe and all the gear, and even pick you up at the end of your trip and shuttle you back to your car. You can paddle for a day, or for several days.

Dinosaur National Monument, Utah/Colorado. One park, two rivers. The Green River that flows south out of Wyoming on its way to the confluence with the Colorado River at Canyonlands National Park and the Yampa River that flows out of the state of Colorado down to the confluence with the Green at Steamboat Rock in Dinosaur are two excellent choices. The Green is run all summer by private and commercial raft trips, while the Yampa's rafting season runs out usually in early July, when skilled kayakers and even canoeists can have the river to themselves.

Canyonlands National Park, Utah. Canyon country in southern Utah gets awfully hot in summer, which is a perfect excuse to turn to the Colorado River that runs through this park. Canoeists looking for a nice flat water paddle can take several days to head from Green River, Utah, north of the park, down to a takeout at Mineral Bottom, just north of Canyonlands, or continue on all the way to the confluence with the Colorado River. There you can arrange to have a powerboat meet you to take you back to Moab, or, if you're up for a challenge, paddle up the Colorado to Moab. Another option is to sign on for a two-day trip down the Colorado through Cataract Canyon, one of the iconic stretches of this majestic river.

Channel Islands National Park, California. You can easily combine a day of sea kayaking at this off-shore park in the Pacific with a few days of camping on the park's islands. Park officials say "backcountry camping is available year-round at the Del Norte campsite near Prisoners Harbor on Santa Cruz Island. Also, during certain times of year, backcountry beach camping is allowed on Santa Rosa Island." For an unusual "surf and turf" vacation, consider sea kayaking for a day through some of the park's sea caves, followed by a few days of camping.

New River Gorge National River, West Virginia. A big difference between Western rivers, such as the Green River through Dinosaur, and Eastern rivers, such as the New, is that Eastern rivers are much more compact: you encounter many more rapids per mile than you do in the West. That's a fact that can easily see you run more rapids on your day trip on the New than you might see on a multi-day trip on the Yampa.

Alaska opens up a whole 'nother chapter in floating in the National Park System, one that requires a good deal of planning (for Lower 48ers), and expertise in many cases. Those opportunities deserve a story of their own....