The fortified city of Kronstadt is located on the island and forms part of a World Heritage Site that is Saint Petersburg and Related Groups of Monuments.

The island is mentioned in the 13th century treaty of Novgorod with Hanseatic League and Gotland, once as "Kotlign" and twice as "Kotling".

[4][5] Off Kronstadt is Fort Alexander, an artificial island that housed a research laboratory on plague and other bacterial diseases, from 1898 to 1917.

The eastern or broad end is occupied by the city of Kronstadt, and shoals extend for 2.4 km (1.5 mi) from the western point of the island to the rock on which the Tolbaaken lighthouse is built.

[2] The island thus divides the seaward approach to St Petersburg into two channels; that on the northern side is obstructed by shoals which extend across it from Kotlin to Lisiy Nos; the southern channel, the highway to the former capital, is narrowed by a spit which projects from opposite Lomonosov on the Russian mainland, and, lying close to Kronstadt, has been historically strongly guarded by batteries.