USS Darter (SS-227)

The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. The laying of the keel is often the initial step in the construction of a ship. In the British and American shipbuilding traditions, this event marks the beginning date of a ships construction.

Groton is a town in New London County, Connecticut located on the Thames River. It is the home of General Dynamics Electric Boat, which is the major contractor for submarine work for the United States Navy. The Naval Submarine Base New London is located in Groton, and the pharmaceutical company Pfizer is also a major employer. Avery Point in Groton is home to a regional campus of the University of Connecticut. The population was 38,411 at the 2020 census.

Connecticut is the southernmost state in the New England region of the Northeastern United States. As of the 2020 United States census, Connecticut was home to over 3.6 million residents, its highest decennial count count ever, growing every decade since 1790. The state is bordered by Rhode Island to its east, Massachusetts to its north, New York to its west, and Long Island Sound to its south. Its capital is Hartford, and its most populous city is Bridgeport. Historically, the state is part of New England as well as the tri-state area with New York and New Jersey. The state is named for the Connecticut River which approximately bisects the state. The word "Connecticut" is derived from various anglicized spellings of "Quinnetuket”, a Mohegan-Pequot word for "long tidal river".

Ceremonial ship launching involves the performance of ceremonies associated with the process of transferring a vessel to the water. It is a nautical tradition in many cultures, dating back thousands of years, to accompany the physical process with ceremonies which have been observed as public celebration and a solemn blessing, usually but not always, in association with the launch itself.

Chuuk Lagoon, previously Truk Atoll, is an atoll in the central Pacific. It lies about 1,800 kilometres northeast of New Guinea, and is part of Chuuk State within the Federated States of Micronesia (FSM). A protective reef, 225 kilometres (140 mi) around, encloses a natural harbour 79 by 50 km, with an area of 2,130 km2 (820 sq mi). It has a land area of 93.07 square kilometres, with a population of 36,158 people and a maximal elevation of 443 metres (1,453 ft). Weno city on Moen Island functions as both the atoll's capital and the state capital, and is the largest city in the FSM with its 13,700 people.

Milne Bay is a large bay in Milne Bay Province, south-eastern Papua New Guinea. More than 35 kilometres long and over 15 kilometres wide, Milne Bay is a sheltered deep-water harbor accessible via Ward Hunt Strait. It is surrounded by the heavily wooded Stirling Range to the north and south, and on the northern shore, a narrow coastal strip, soggy with sago and mangrove swamps. The bay is named after Sir Alexander Milne.

A depth charge is an anti-submarine warfare (ASW) weapon. It is intended to destroy a submarine by being dropped into the water nearby and detonating, subjecting the target to a powerful and destructive hydraulic shock. Most depth charges use high explosive charges and a fuze set to detonate the charge, typically at a specific depth. Depth charges can be dropped by ships, patrol aircraft, and helicopters.

Brisbane is the capital and most populous city of Queensland, and the third-most populous city in Australia and Oceania with a population of approximately 2.6 million. Brisbane lies at the centre of South East Queensland, which includes several other regional centres and cities. The central business district is situated within a peninsula of the Brisbane River about 15 km (9 mi) from its mouth at Moreton Bay. Brisbane is located in the hilly floodplain of the Brisbane River Valley between Moreton Bay and the Taylor and D'Aguilar mountain ranges. It sprawls across several local government areas, most centrally the City of Brisbane. The demonym of Brisbane is Brisbanite.

Davao City, officially the City of Davao, is a 1st class highly urbanized city in the Davao Region, Philippines. The city has a total land area of 2,443.61 km2 (943.48 sq mi), making it the largest city in the Philippines in terms of land area. It is the third-most populous city in the Philippines after Quezon City and Manila, and the most populous in Mindanao.  According to the 2020 census, it has a population of 1,776,949 people.

Darwin is the capital city of the Northern Territory, Australia. With an estimated population of 147,255 as of 2019, the city contains the majority of the residents of the sparsely populated Northern Territory.

Manus Island is part of Manus Province in northern Papua New Guinea and is the largest of the Admiralty Islands. It is the fifth-largest island in Papua New Guinea, with an area of 2,100 km2 (810 sq mi), measuring around 100 km × 30 km. Manus Island is covered in rugged jungles which can be broadly described as lowland tropical rain forest. The highest point on Manus Island is Mt. Dremsel, 718 metres (2,356 ft) above sea level at the centre of the south coast. Manus Island is volcanic in origin and probably broke through the ocean's surface in the late Miocene, 8 to 10 million years ago. The substrate of the island is either directly volcanic or from uplifted coral limestone.

Halmahera, formerly known as Jilolo, Gilolo, or Jailolo, is the largest island in the Maluku Islands. It is part of the North Maluku province of Indonesia, and Sofifi, the capital of the province, is located on the west coast of the island.

Mindanao is the second-largest island in the Philippines, after Luzon, and seventh-most populous island in the world. Located in the southern region of the archipelago, the island is part of an island group of the same name that also includes its adjacent islands, notably the Sulu Archipelago. According to the 2020 census, Mindanao has a population of 26,252,442 people, while the entire island group has an estimated population of 27,021,036 according to the 2021 census.

Tsugaru (津軽) was a large minelayer of the Imperial Japanese Navy that was in service during the early stages of World War II. She was named after the Tsugaru Peninsula in northwest Aomori Prefecture of Japan. She was commissioned immediately before the start of World War II, and sunk by the American submarine USS Darter in June 1944.

Morotai Island is an island in the Halmahera group of eastern Indonesia's Maluku Islands (Moluccas). It is one of Indonesia's northernmost islands.

The Celebes Sea, or Sulawesi Sea, of the western Pacific Ocean is bordered on the north by the Sulu Archipelago and Sulu Sea and Mindanao Island of the Philippines, on the east by the Sangihe Islands chain, on the south by Sulawesi's Minahasa Peninsula, and on the west by northern Kalimantan in Indonesia. It extends 420 miles (675 km) north-south by 520 mi (840 km) east-west and has a total surface area of 110,000 square miles (280,000 km2), to a maximum depth of 20,300 feet (6,200 m). South of the Cape Mangkalihat, the sea opens southwest through the Makassar Strait into the Java Sea.