Semiachksky Estuary is among the unique natural sites of Kronotsky National Biosphere Reserve and marks its southern boundary. It covers an area of 70ha and makes a sort of lagoon whose shallowness enables the water to get quite warm in summer. The estuary is the result of the joint activities of Kronotsky bay and rivers and streams such as Novy Semiachik and Stary Semiachik.
Many sea bird species come to nest on its swampy shores and at low tide, they find food in abundance. It is possible to meet, among others, about 150 couples of Aleutian Terns, River Terns, seagulls, gulls and ducks. Semiachksky Estuary is also a wintering place for more 1,200 Anseriformes individuals as well as whopper swans and solitary snipes.
The estuary is also known for serving as a transit zone for several species of Pacific salmons who come to spawn in the nearby rivers and streams. They are then a delight for fisher birds, bears, otters and many other animals. In addition to the salmons, graylings, sticklebacks and navagas can be found in the water. It is also note worthy that the estuary’s shores are inhabited by Steller’s sea eagles, and foxes.
Finally, in autumn and winter Semiachksky Estuary serves as a vacation spot for seals from various families.