Peterson Bay extends approximately 2 miles (3.2 km) from Peterson Point into the Kenai Peninsula on the southeastern shore of Kachemak Bay in lower 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 consists mainly of basalt and chert, part of the McHugh Complex. This formation is included in the Southern Margin composite terrane, which accreted to the western margin of the North American Plate during the Mesozoic era. Cook Inlet fills a basin between two belts of Mesozoic and younger rocks along southern Alaska’s margin. Partially filling the basin, and exposed on both east and west sides, is a sequence of mostly continental sedimentary rocks from the Paleogene period, up to 23,000 feet (7,000 m) thick. These rocks are significant oil and gas reservoirs, with petroleum likely originating from underlying Jurassic and Triassic rocks. The present-day landscape of Kachemak Bay is the result of repeated glaciations during the Pleistocene epoch. The most recent was the Naptowne glaciation, when a large ice cap covered the Aleutian Range on the west side of Cook Inlet. Ice advanced south and eastward from the vicinity of Tuxedni Bay. Ice flowing east from this ice cap coalesced with ice moving westward from the Harding Icefield and out of Kachemak Bay. This combined ice mass completely filled the floor of the lower Cook Inlet, forming a barrier that created a proglacial lake. The Homer Spit likely formed during this period, while the Archimandritof Shoals are probably remnants of an outwash plain that developed as the glacier in Kachemak Bay retreated. A smaller shoal, extending to Gull Island from the peninsula separating Peterson Bay from China Poot Bay, likely shares a similar origin and timeline.

The archaeological record of Kachemak Bay dates back approximately 4,500 years. Artifacts from the area reflect various periods defined by technological changes and adaptations. The earliest known inhabitants were of the Ocean Bay tradition, who navigated the Shelikof Strait and lower Cook Inlet in small, skin-covered boats. They are considered ancestors of the present-day Alutiiq people. Around 4,000 years ago, the Arctic Small Tool tradition appeared in Kachemak Bay. These people employed technologies developed along the Alaska Peninsula and the eastern Bering Strait, such as scrapers and blades, and likely introduced the bow and arrow. The most studied archaeological period in the area is the Kachemak tradition, which began around 3,000 years ago and ended about 1,500 years ago. After 500 AD, evidence confirms continuous use of the region by the Dena’ina Athabascan and Alutiiq groups. Between 1881 and 1883, Norwegian ethnographer Johan A. Jacobsen explored Alaska and collected a significant number of artifacts. At Fort Alexander, now Nanwalek, he found the entire population occupied with sea otter hunting. He learned about the ruins of a deserted Native settlement called Soonroodna, or Hardak, at the foot of the third glacier on the south shore of Kachemak Bay. Soonroodna was a sizable village even before Russian fur traders arrived in 1794. Shortly after building Fort Saint Nicholas at the Kenai River, the Russians raided Soonroodna. They traveled in many boats, took many young girls and women back to the fort, and kept them as wives. In sorrow, the remaining Natives realized they were powerless against the Russians, left their village, and 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 supports a small community, mainly comprising summer residences, lodges, a field station for the Center for Alaskan Coastal Studies, and oyster farms. The Pacific oyster (Crassostrea gigas) was imported from Japan to Puget Sound, Washington, in the early 1900s to replace the declining populations of the native Olympia oyster (Ostrea lurida), which suffered from pollution and habitat destruction. Initial seed transplants to oyster farms were successful, with excellent growth and natural reproduction facilitating sustained harvests. By 1946, the industry reached 1.5 million gallons of shucked oysters. The fishery expanded from Puget Sound to Willapa Bay, historically accounting for about two-thirds of the state’s total harvest. Since 1957, Washington’s commercial fishery of native oysters has been replaced by aquaculture. Alaska began importing Pacific oysters in 1909, planting seed oysters on intertidal beaches from Ketchikan to Kachemak Bay. Production of shucked oysters peaked at 550 gallons (2,081 l) in 1943, with the industry surviving only in the southernmost regions. However, unwieldy regulations and the remoteness of farms eventually led to its demise in 1967. Oyster aquaculture in Alaska restarted in the late 1970s to supply live oysters to the restaurant market. In 1989, the State of Alaska passed legislation regulating the farming of approved shellfish species in coastal waters, including Pacific oysters, clams, mussels, and scallops. By 1993, approximately ten oyster farms were established in Kachemak Bay. In Kachemak Bay, oysters are mainly grown in lantern nets suspended in the water from floating buoys. This method allows them to feed continuously on plankton and avoid seasonal extreme air temperatures, mud, and sand. It takes about three years for oyster larvae to reach marketable size. By 2010, the industry had expanded to 45 farms, spanning from Annette Island in southeastern Alaska to Kachemak Bay. Read more here and here. Explore more of Peterson Bay and Kachemak Bay here: