Mexico's underwater river (and friends).

The word "cenote" comes from a Mayan word meaning "well" and is used to describe sinkholes that have exposed rocky walls and contain groundwater. The water in these cenotes is often very clear since it comes from rain water slowly infiltrating through the ground. They are often the result of cave roofs collapsing to reveal extensive flooded cave systems beneath. These systems can have subterranean tunnels that reach all the way to the ocean. If such a cenote is a landlocked body of water whose tunnels lead to the ocean, it's what's known as an anchialine pool. In these pools, the pure rainwater floats atop the denser saline water from the sea. The sharp change in salt concentration over a small change in depth causes a blurry swirling effect due to the refraction between the different densities. Cool!
So one such body of water is the Cenote Angelita in Mexico. It's not an achialine pool, but goes straight down 200 feet. The first hundred are freshwater, and the last hundred are salt water--the extraordinary part is the layer of hydrogen sulfate that separates the two. Not only that, but there are trees at that depth as well, making it look like a most beautiful and eerie underwater river.
Quintana Roo, Mexico is home to the Ox Bel Ha ("Three Paths of Water") cave system, which is the longest explored underwater cave in the world, with 110 miles of underwater passages.
Other flooded cave systems include Dos Ojos, and the now combined Nohoch Nah Chich/Sac Actun cave system, both of which are also in Mexico near the Caribbean coast of the Yucatan Peninsula in Quintana Roo. Dos Ojos has no less than 25 sinkhole entrances and more than 20,000 feet of caves and tunnels. It also contains the deepest known cave passage in Quintana Roo, a cenote known as "The Pit" measuring at 396 feet.
These caves are super popular for diving, and of course, swimming!

Signmark

A coworker and I have been writing raps about Starbucks just for fun, and reading about rapping today I found out about a deaf rapper from Finland who goes by the name of Signmark. Marko Vuoriheimo is a 32 year old native of Helsinki who was born into a signing family. He believes that the deaf community should not be seen as a disabled one, but rather a linguistic minority with their own culture and history. Apparently he has signed poetry and music since he was a child, although he didn't start creating his own music until 2004. He rhymes his signs by making sure they have the same sort of hand form, and the bass line helps him follow the music and time his rhymes. He starts by using giant headphones to "listen" to music made by a friend where he concentrates on the rhythm of the bass to get the flow to rhyme his words and signs.

Musical sculptures?!

Around the world, people have gotten pretty clever with manipulating natural phenomenons (phenomena?) in order to produce music. The Sea Organ, for example, is an architectural object in Croatia which is a series of tubes and a resonating cavity underneath marble steps at the shore of the ocean, whose waves and wind create random notes. The sculpture was designed by a man named Nikola Bašić, is 230 feet long and has 35 pipes built under the concrete. The harmonies change as you walk along the promenade but are never dissonant despite the randomness of the sea and wind, since the pipes were all tuned to be able to sound good together. A similar object in San Francisco is the Wave Organ, another acoustic sculpture that rather than being particularly musical, tends to amplify the sounds of the sea's rumbles, gurgles, and sloshes through a series of pipes that interact with the tide and project the sounds to listeners at different stations. Lastly, the High Tide Organ is a structure attached to the sea wall in Blackpool, England that uses the force of the tides to produce the harmonic series in B flat. At high tide, the swell of the sea pushes air up through 18 organ pipes built within the sculpture, causing it to sound.
On another note, the Singing Ringing Tree is a sound sculpture in the northwest of England that generates discordant, haunting sounds as the western winds of the moor blow through it. It stands at about 10 feet tall, is composed of galvanized steel pipes, and covers a range of several octaves.
Also in the group of musical sculptures are singing roads, or musical roads, the first of which was created in 1995 in Denmark by Steen Krarup Jensen and Jakob Freud-Magnus, who called their creation the Asphaltophone. It's made of a series of raised pavement markers. The Melody Road and Singing Road in Japan and Korea respectively, are musical roads constructed of a series of grooves carved into the pavement at intervals. The tunes are based on the depth and spacing of the grooves, as at close intervals they produce higher sounds, and at widely spaced intervals, they produce deeper ones. In Japan there are three Melody Roads, and in Korea there is only the one. The one in Korea was designed specifically to help motorists stay alert and awake, whereas the Japanese ones were constructed for tourism. Also, the Civic Musical Road is a quarter-mile stretch of road in Lancaster, California, whose grooves cause the finale of the William Tell Overture to resound as you drive over it.