Peterson Bay extends about 2 miles (3.2 km) from Peterson Point into the southeastern shore of Kachemak Bay on the Kenai Peninsula and the eastern shore of Cook Inlet, about 18 miles (29 km) northeast of Seldovia and 10 miles (16 km) southeast of Homer, Alaska. The local name was first reported in the 1940s on maps by the U.S. Geological Survey or U.S. Coast and Geodetic Survey. The bedrock surrounding Peterson Bay is composed mostly of basalt and chert in a geological formation called the McHugh Complex which is part of the huge Southern Margin composite terrane that accreted to the western margin of the North American plate during the Mesozoic period. Cook Inlet fills a basin lying between two belts of Mesozoic and younger rocks along the southern Alaska margin. Partially filling the basin and exposed on both east and west sides is a sequence of mostly continental sedimentary rocks that formed during the Tertiary and is as much as 23,000 feet (7,000 m) thick. These rocks are important oil and gas reservoirs for petroleum thought to be from the underlying Jurassic and Triassic rocks. The present-day landscape of Kachemak Bay is the result of repeated glaciations during the Pleistocene. The most recent was the Naptowne glaciation when a large ice cap area covered the Aleutian Range on the west side of Cook Inlet and ice advanced south and eastward from the vicinity of Tuxedni Bay. Ice flowing eastward from this ice cap coalesced with ice flowing westward from the Harding Icefield and out of Kachemak Bay. This coalescing ice completely filled the floor of the lower part of Cook Inlet and formed a barrier in the lower part of Cook Inlet that created a proglacial lake. It is likely that the Homer Spit was formed at this time and the Archimandritof Shoals are the remains of an outwash plain that formed when the glacier filling Kachemak Bay retreated. A smaller shoal extending to Gull Island from the peninsula separating Peterson Bay from China Poot Bay probably has a similar origin and timeline.

The archaeological record in Kachemak Bay dates from about 4,500 years ago. Artifacts encompass different archaeological periods defined by changes or adaptations in technology. The earliest known humans to inhabit Kachemak Bay were of the Ocean Bay tradition who navigated Shelikof Strait and lower Cook Inlet in small skin-covered boats and are considered the ancestor of the present-day Alutiiq people. Around 4,000 years ago, the Arctic Small Tool tradition appeared in Kachemak Bay. These people used technology that developed along the Alaska Peninsula and on the eastern shores of the Bering Strait including scrapers and blades, and they were probably the first to introduce the bow and arrow. The archeological period most studied in the area is known as the Kachemak tradition, which came to the area around 3,000 years ago, and then stopped using the bay about 1,500 years ago. After about 500 AD, archeological evidence confirms the continuous use of the area by Dena’ina Athabascan and Alutiiq groups. From 1881 to 1883, Johan A. Jacobsen, a Norwegian ethnographer, explored Alaska and amassed a large collection of artifacts. At Fort Alexander, now Nanwalek, he found the entire population was occupied with sea otter hunting but learned about the ruins of an old deserted Native settlement called Soonroodna or Hardak situated at the foot of the third glacier on the south shore of Kachemak Bay. Soonroodna was a village of considerable size even before the arrival of Russian fur traders in 1794. Shortly after they had built Fort Saint Nicholas at the Kenai River the Russians went to Soonroodna in many boats to carry out a raid and they took as many of the young girls and women as they could back to the fort and kept them as wives. In deep sorrow, the remaining Natives left their village because they realized that against the Russians they were powerless, and they scattered among the villages on Kodiak Island. Jacobsen found many signs of human habitation and collected potsherds, a harpoon for sea otter and seal hunting, and several knives. In 2018, the Foundation for Prussian Cultural Heritage returned the Native artifacts to Alaska.

Peterson Bay now supports a small community that includes mostly summer residences, lodges, a field station for the Center for Alaskan Coastal Studies, and oyster farms. The Pacific oyster, Crassostrea gigas, was imported in the early 1900s from Japan to Puget Sound, Washington as a substitute for the declining populations of the native Olympia oyster, Ostrea lurida, which was devastated by pollution and habitat destruction. Initial seed transplants to oyster farms were successful, and excellent growth and natural reproduction enabled sustained harvests and revitalization of the fishery, which reached 1.5 million gallons of shucked oysters by 1946. The fishery expanded from Puget Sound to Willapa Bay on the Washington outer coast, which historically produced approximately two-thirds of the total state harvest. Since 1957, the Washington commercial fishery of native oysters has been replaced by aquaculture. Alaska began importing Pacific oysters in 1909, and seed oysters were planted on intertidal beaches from Ketchikan to Kachemak Bay. Production peaked at 550 gallons of shucked oysters in 1943 with the industry surviving only in the southernmost regions. The demands of unwieldy regulations and difficulties with the remoteness of the farms eventually led to the industry’s demise in 1967. Alaska oyster aquaculture restarted in the late 1970s to produce live oysters for the restaurant market. In 1989, the State of Alaska passed legislation regulating the farming of approved shellfish species in coastal waters including the Pacific oyster, clams, mussels, and scallops. By 1993, approximately 10 oyster farms were established in Kachemak Bay. Oysters in Kachemak Bay are mostly grown in lantern nets suspended in the water from floating buoys so they can feed continually on plankton and avoid exposure to seasonal extreme air temperatures as well as mud and sand. In Kachemak Bay, it takes approximately three years for the oyster larvae to grow to marketable size. In 2010, the industry consisted of 45 farms spread from Annette Island in southeastern Alaska to Kachemak Bay. Read more here and here. Explore more of Peterson Bay and Kachemak Bay here: