Pearl hunting or pearl diving refers to a largely obsolete method of retrieving pearl

Pearl

A pearl is a hard object produced within the soft tissue of a living shelled mollusk. Just like the shell of a mollusk, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other...

s from pearl oyster

Pearl oyster

Pearl oysters are saltwater clams, marine bivalve molluscs of the genus Pinctada in the family Pteriidae. They have a strong inner shell layer composed of nacre, also known as "mother of pearl"....

s, freshwater pearl mussel

Freshwater pearl mussel

The freshwater pearl mussel, scientific name Margaritifera margaritifera, is an endangered species of freshwater mussel, an aquatic bivalve mollusc in the family Margaritiferidae....

s and, on rare occasions, other nacre

Nacre

Nacre , also known as mother of pearl, is an organic-inorganic composite material produced by some mollusks as an inner shell layer; it is also what makes up pearls. It is very strong, resilient, and iridescent....

-producing molluscs, such as abalone

Abalone

Abalone , from aulón, are small to very large-sized edible sea snails, marine gastropod molluscs in the family Haliotidae and the genus Haliotis...

.
Before the beginning of the 20th century, the only means of obtaining pearls was by manually gathering very large numbers of pearl oysters (or pearl mussels) from the ocean floor (or lake, or river bottom). The bivalves were then brought to the surface, opened, and the tissues searched.