Sea glass is glass

Glass

Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...

 found on beach

Beach

A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...

es along ocean

Ocean

An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

s, bays, rivers, gullies or large lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

s that has been tumbled and smoothed by the waves, water and sand, creating smooth, frosted shards of glass.

Combing shorelines for sea glass is a hobby for many beach-goers either simply to collect, or to craft into jewelry or other decorative pieces.
Sea glass can be found all over the world, but the beaches of the northeast United States, California, northwest England, Mexico, Hawaii, Puerto Rico, Nova Scotia, Australia, Italy and southern Spain are famous for their bounty of sea glass, bottles, bottle lips and stoppers, art glass, marbles, and pottery shards.