Jack Bay is an estuary surrounded by the Chugach Mountains that extends southeast for 6 miles (10 km) from Valdez Arm in Prince William Sound, about 70 miles (113 km) northeast of Whittier and 12 miles (19 km) southwest of Valdez, Alaska. In 1898, the bay was named by Captain William R. Abercrombie of the U.S. Army, reputedly for W.G. Jack, a prospector who was exploring for gold at that time. Valdez Arm is a passage that connects Prince William Sound and Port Valdez and was named after the Spanish naval officer Antonio Valdes y Basan in 1790, by Salvador Fidalgo. Jack Bay is a deglaciated fjord aligned with a contact fault in the Southern Margin Composite terrane that separates sedimentary rocks of the Valdez Group from rocks in the Orca Group. Rocks of the Valdez Group comprise greywacke sandstone and slate cut by several quartz veins containing gold, pyrite, pyrrhotite, and arsenopyrite. A portion of Jack Bay is now an Alaska State Marine Park.
In 1983, the first Alaska marine park opened near Juneau as part of an international system extending from Washington through British Columbia to Alaska. This system provides boat owners and water enthusiasts access to coastal environments with protected anchorages. In 1990, the marine park system expanded to include seven parks in Prince William Sound and Resurrection Bay. Today, there are 35 state marine parks in Alaska, ranging in size from the 62 acres (25 ha) Joe Mace Island State Marine Park east of Wrangell to the massive 103,600 acres (41,925 ha) St. James Bay State Marine Park, about 30 miles (48 km) northwest of Juneau on the west shore of Lynn Canal. These 35 parks are mostly undeveloped and represent diverse habitats from vast exposed stretches of pristine coastline to sheltered embayments like Jack Bay.
The entrance to Jack Bay is on the east shore of Valdez Arm, south of Valdez Narrows, between Entrance Point to the north and Tongue Point to the south. Jack Bay has intertidal mudflats at the head of the bay and numerous submerged and intertidal boulders. The uplands consist of alder, muskeg, salt marsh, and old growth forest of spruce and hemlock. An island in the middle of the bay has a protected bight on the southern end with four campsites and is surrounded by several smaller islets and numerous rocks. This island and the adjacent mainland are part of Jack Bay State Marine Park. The park is 1,544 acres (625 ha) surrounded by steep mountains and a spruce-hemlock forest. There are no roads and the only access is by boat or floatplane. The park has a rustic public-use cabin that sleeps six. Read more here and here. Explore more of Jack Bay and Valdez Arm here: