San Marcos River in TexasThe San Marcos River is clear because it is fed by a freshwater spring. Not only is this water clear, but it is also extraordinarily clean. It is ten times cleaner than the FDA drinking water requirements.
In the next year an army engineer's report mentioned the Trinity as the deepest and least obstructed river in Texas, said that seven steamboats were in operation in its lower channel, and estimated that navigation was practicable.
The great news is, swimming in Texas lakes is just as safe as swimming in any natural body of water, taking into account the possible risks outlined above.
The Weddell Sea has been claimed by scientists to have the clearest waters of any ocean in the world. Described by a historian as “the most wretched and dismal region on earth”, due to the flash freezes that caught Shackleton's ship, its clarity is only belied by the sheer depth of the ocean below.
Water SchoolNatural lakes have been a rare commodity in Texas. In fact, the state had only one natural lake, Caddo Lake in East Texas, that was formed by a log jam. A permanent dam was installed at the lake in the early 20th century.