Nepean Bay
Nepean Bay Location in South Australia
Location	Kangaroo Island, South Australia
Coordinates	35°40′57″S 137°44′43″E / 35.68250°S 137.74528°E / -35.68250; 137.74528[1]
Type	Bay
Basin countries	Australia
Max. length	30 km (19 mi).[2]
Max. width	30 km (19 mi)[2]
Max. depth	13.4 m (44 ft)[2]
Islands	Busby Islet, Beatrice Islets
Settlements	Kingscote Cygnet River Brownlow KI Nepean Bay American River Baudin Beach Island Beach

Nepean Bay is a bay on the northeast coast of Kangaroo Island in South Australia. It is about 130 km (81 mi) south-southwest of Adelaide. The British explorer Matthew Flinders named it after Sir Evan Nepean on March 21, 1802.

Nepean Bay is between Point Marsden and Kangaroo Head on Kangaroo Island’s northeast coast. It faces Investigator Strait. The bay includes three smaller parts from west to east: Bay of Shoals, Western Cove, and Eastern Cove. Eastern Cove has a channel called American River and a lagoon called Pelican Lagoon.

Bay of Shoals is just north of the town of Kingscote. Its entrance is between Cape Rouge in the north and Beatrice Point in the south, about 5 km (3.1 mi) wide. The bay is shallow, with a maximum depth of 2.7 m (8 ft 10 in). A spit called "The Spit" stretches from Cape Rouge toward Beatrice Point and includes small islands called Busby and Beatrice. This spit is sometimes exposed during low tides. Boats can enter the bay through a natural channel near Beatrice Point.^[3][2]

Kingscote Harbour is the calm water area between Bay of Shoals and Western Cove. It is protected by the Beatrice Islets and is near the northern part of Kingscote town.^[4]

Western Cove’s entrance is between Beare Point in the west and Morrison Point in the east, about 15 km (9.3 mi) wide. The cove is up to 10 m (33 ft) deep at its entrance. The south shore has high rocky cliffs and wooded hills that slope down to the west. There are red cliffs and sandy beaches, and the land near the back of the cove is low and swampy.^[5]

Eastern Cove’s entrance is between Morrison Point in the west and Kangaroo Head in the east, about 11 km (6.8 mi) wide. It is up to 14 m (46 ft) deep at the entrance. The shore between Kangaroo Head and American Beach is rocky. Between American Beach and Rocky Point, there are beaches and rocky points. A sandy beach runs along the south shore between Rocky Point and Strawbridge Point. The land behind the south shore is low with wooded hills. Eastern Cove also includes Ballast Head Harbor near Ballast Head.^[6]

Matthew Flinders named Nepean Bay after Sir Evan Nepean, the First Secretary to the Admiralty, on March 21, 1802.^[7]

Towns around Nepean Bay include Kingscote, Brownlow KI and Nepean Bay on the shores of Western Cove, and American River, Baudin Beach and Island Beach on the shores of Eastern Cove.^[8]

There are several protected areas in and near Nepean Bay:

• Aquatic reserve: American River.^[9]
• Conservation parks: Beatrice Islet, Busby Islet, Cygnet Estuary, Nepean Bay and Pelican Lagoon.^[10]
• Marine park: Encounter Marine Park^[11]

• Boating Industry Association of South Australia (BIA); South Australia. Department for Environment and Heritage (2005), South Australia's waters an atlas & guide, Boating Industry Association of South Australia, ISBN 978-1-86254-680-6
• Anon (1987). Conservation Parks of Kangaroo Island Management Plan (PDF). Adelaide: Department of Environment and Planning, South Australia (DEP). ISBN 0-7243-8983-0.
• "Encounter Marine Park Management plan summary" (PDF). Department of Environment, Water and Natural Resources (DEWNR). Retrieved 17 June 2014.
• South Australia. Department of Marine and Harbors (DMH) (1985), The Waters of South Australia a series of charts, sailing notes and coastal photographs, Dept. of Marine and Harbors, South Australia, ISBN 978-0-7243-7603-2
• Flinders, Matthew (1966) [1814]. A Voyage to Terra Australis : undertaken for the purpose of completing the discovery of that vast country, and prosecuted in the years 1801, 1802, and 1803 in His Majesty's ship the Investigator, and subsequently in the armed vessel Porpoise and Cumberland Schooner; with an account of the shipwreck of the Porpoise, arrival of the Cumberland at Mauritius, and imprisonment of the commander during six years and a half in that island (Facsimile ed.). Adelaide: Libraries Board of South Australia. Retrieved 27 March 2013.
• "American River Aquatic Reserve" (PDF). Primary Industries and Regions SA (PIRSA). Archived from the original (PDF) on 5 April 2015. Retrieved 6 January 2014.