Lake Malawi, Malawi
Home to 1,000 species of fish—estimated to be more than anyplace on earth—Lake Malawi (also called Lake Nyasa) is Africa's third largest lake at 363 miles long and up to about 50 miles wide in spots. Located in a depression 2,300 feet below sea level, it's positioned at the crossroads of Malawi, Mozambique and Tanzania, and supports hundreds of local villages with its rich underwater stock (which is, unfortunately, gradually being depleted due to over-fishing). The lake's southern portion—as well as a bordering nub of wildlife-rich land, Cape Maclear—represents the world's first freshwater national park; it was also named a UNESCO World Heritage Site in 1984. A star of the waters here is the mbuna, a native freshwater fish known for eating directly from people's hands. Bring your snorkel gear—as beautiful as the scenery is, the best part about Lake Malawi is what's swimming beneath you in the crystal clear water.
Peyto Lake, Alberta CanadaAlberta's Lake Louise is the famous one, on all the postcards and posters. But Louise's sister lake 29 miles north along Icefields Parkway, a two-laner that winds 142 miles through the Canadian Rockies, is even more picturesque. Thanks to glacial rock flour that flows in when the ice and snow melt every summer, the waters of Banff National Park's Peyto Lake are a brilliant turquoise more often associated with warm-weather paradises like Antigua and Bora-Bora. For the most dramatic views of the 1.7-mile-long stunner, encircled with dense forest and craggy mountain peaks, pull into the lot at Bow Summit, the parkway's highest point, and follow the steep hike to the overlook.
Crater Lake, Oregan
Thousands of years ago, the top of a 12,000-foot-high volcano in the Cascade Range exploded. The massive pit left behind became known as Crater Lake, the centerpiece of a national park in southern Oregon that displays nature at its rawest and most powerful. Forests of towering evergreens and 2,000-foot-high cliffs surround the lake, where extraordinarily deep waters—at 1,943 feet, it's the deepest lake in the United States—yield an intense sapphire-blue hue. If winter hiking and cross-country skiing aren't your thing, wait until early July to visit, when the roads have been plowed and the trails cleared. Rim Drive, a 33-mile road that encircles the lake, has picture-perfect views from all sides. For a closer look, follow the mile-long Cleetwood Cove Trail to the shore. Brace yourself before diving in: The water temperature rarely rises above 55 degrees Fahrenheit.
Taal Lake, Philippines
This dangerous beauty, situated just 37.28 miles south of Manila, has two distinct claims to fame: It is the deepest lake in the Philippines, with a depth of 564 feet. It is also home to one of the world's smallest but most active volcanoes, the Taal Volcano, which sits within its waters on the island of Luzon. The lake itself was formed when a larger volcanic crater here collapsed; now seismologists spend a lot of time monitoring this spot for tremors, and sending out frequent eruption warnings through the country's Department of Tourism. Plenty of tour groups offer trips to the natural wonder—in spite of the fact that it has been declared a permanent danger zone. A safer way to see the volcano is by taking a drive along the Tagaytay-Taal ridge in nearby Tagaytay City.
Lake Atitlán, Guatemala
Nearly a mile up in the highlands of Guatemala, Atitlán (Lago de Atitlán) rests at the foot of three massive conical volcanoes. Small Mayan villages line its shores, which are set off by steep hills draped with oak and pine trees and nearly 800 plant species. There's no single, must-see view of the lake, so try several vantage points: from up high on Highway 1; from the town of Panajachel, the buzzing market hub that juts out into the water; or aboard a lancha, one of the many small boats that ferry visitors from village to village. We're saddened to note that the lake has built up high levels of blue-green algae over the years (in October and November 2009, a film of green scum began briefly marring its surface; since then there have been ambitious efforts to solve the problem.
Loch Lomond, Scotland
With a backdrop of windswept rolling hills and medieval castles, Loch Lomond feels like it's straight out of a Victorian romance novel. The 24-mile-long lake is dotted with islands, some so small that they disappear when the water levels are high, and others large enough to be (sparsely) inhabited. Most ferries stop at the largest island, Inchmurrin (population 11), so visitors can get a look at the remains of a 7th-century monastery and the 14th century Lennox Castle, used often as a hunting lodge for kings.