It is located to the east of the Danish island of Amager in Tårnby municipality and lies just to the west of the sea border between Denmark and Sweden.

A series of islets, inlets and rock deposits from the last ice age appear at the south end of the island.

Saltholm's vegetation is dominated primarily by grasses, with its landscape consisting mainly of flat chalk meadowlands and coastal meadow.

[8] The existence of the island is first attested in 1230, when King Valdemar II of Denmark is recorded as having given Saltholm to Bishop Niels Stigsen of the see of Roskilde.

[11] The cows of Saltholm were commemorated in the late 19th century by the Danish painter Theodor Philipsen, who travelled frequently to the island to paint its cattle and treeless landscapes.

Most of the guns were mounted on barbette carriages and protected by armoured shields and concrete and earthen ramparts.

[14] Saltholm was the site of an incident resulting in the loss of the British submarine HMS E13, which ran aground on the island on 17 August 1915 due to a faulty compass.

Two days later, two German destroyers attacked the submarine while it was still stranded on the shoreline as the crew worked to refloat the vessel.

[21] However, it was repeatedly delayed; contributory factors included the 1973 oil crisis and its economic fallout, a slump in air travel, and opposition from campaigners concerned about the impact on the fragile environment in the Øresund and around the island.

[22] When the Øresund fixed link was eventually built in the 1990s, it was routed 1 km south of Saltholm to avoid damaging the island and the surrounding shallow waters.