Subterranean River, the Navigable Underground River

Located in the city of Puerto Princesa, Palawan in the Philippines, the Puerto Princesa Subterranean River National Park is a limestone karst mountain landscape with an 8.2 kilometers navigable underground river. This park is included in the UNESCO World Heritage List.

Subterranean River entrance (Source)

The underground river is said to be the world's longest. At the mouth of the cave, a clear lagoon is framed by ancient trees growing right to the water's edge. Monkeys, large monitor lizards, and squirrels find their niche on the beach near the cave.

Inside the Subterranean River (Source)

Inside the Subterranean River (Source)

Inside the cave are major formations of stalactites and stalagmites, and several large chambers.

Subterranean River rock formation (Source)

Subterranean River rock formation (Source)

Subterranean River rock formation (Source)

The most spectacular feature of the river is that it winds through a cave before flowing directly into the South China Sea. The lower portion of the river is subject to tidal influences.

Subterranean River exit (Source)

Mekong River, Asia's 7th Longest River

The Mekong river is the 11th longest river in the world. It run in six countries - China's Yunnan province, Burma, Thailand, Laos, Cambodia and Vietnam. With it's length of 4,350 kilometers, it is the 7th longest river in Asia. It discharges an estimated of 475 km3/114 cu mi of freshwater to the sea annually and it drains an area of 795,000 km2.

Map of Mekong River. Source: hereticdhammasangha.wordpress.com

Because of it's massive size, no wonder Mekong is home to the world's giant freshwater fishes. This giants are now becoming small in number due to human activities.

Giant catfish of Mekong River. Source: nationalgeographic.com

Giant of barb Mekong River. Source: nationalgeographic.com

The name "MEKONG" originate from the Thai language, Mae Nam Khong, which means "Mother-River Khong".

Evening in the Mekong River. Source: flickr.com/photos/hschmid

Mekong river serves as a major transportation and economic route to all villages around it.

Market in the Mekong River. Source: flickr.com/photos/kateyaeger

Two boats in the Mekong River. Source: flickr.com/photos/hschmid

Amazon River, World's Largest River

The Amazon river is the largest and the second longest river in the world. It is so huge that it covers six countries, Peru, Colombia, Brazil, Bolivia, Venezuela, and Ecuador. It has the largest drainage basin in the world and accounts for approximately one fifth of the world's total river flow.

During the dry season, the river covers and area of 110,000 square kilometers, while in the wet season the area rises to 350,000 square kilometers. At its widest point the Amazon River can be 11 kilometers wide during the dry season and 45 kilometers wide during the wet season.

Satellite image of the mouth of the Amazon river. Source: wikipedia.org

A beautiful morning in the Amazon. Source: flickr.com/photos/markgee6

The Amazon river originates from the Apacheta cliff in Arequipa at the Nevado Mismi, with a sole sign of a wooden cross.. Source: wikipedia.org

Amazon river is also home to one of the world's largest fishwater fish, the Pirarucu. Sadly, this fish is dwindling in numbers due to over fishing. Here's a video of a study funded by the National Geographic.

The Grand Canyon, Massive Steep-sided Gorges

The Grand Canyon is a massive steep-sided gorge located in the state of Arizona, USA. It is carved by the Colorado River over a period of six million years. The Grand Canyon is 277 miles long, ranges in width from 4 to 18 miles and attains a depth of more than a mile.

Source: wikipedia.org

Source: wikipedia.org

Source: wikipedia.org