What is "aquascope"

An aquascope (also called bathyscope) is an underwater viewing device. It is used to view the underwater world from dry land or a boat. It eliminates the water surface glare and allows viewing as far as water clarity and light permit. The underwater viewer can be used for observing reefs, checking boat moorings, secchi disks and other survey work. It is also used as educational tool to watch plants, creatures and habitats underneath the surface of rivers, lakes and seas.

A more advanced version, an underwater telescope was patented by Sarah Mather in 1845 - U.S. Patent No. 3,995; it permitted sea-going vessels to survey the depths of the ocean. It used a camphine lamp in a glass globe that was sunk into the water. The device allowed the examination of a ship's hull and other details from the deck of a boat. In 1864 Sarah Mather added an improvement - U.S. Patent No. 43,465 to her previous invention to detect Southern underwater warships.