The main factors relevant were the advance or recession of the Weichselian glaciation responsible for the Fenno-Scandian ice sheet and the isostatic sinking of the landforms due to the weight of ice or rebound when it melts (springing back, post-glacial rebound, glacial isostatic adjustment),[3] and this was known by geologists to be relevant to the Baltic area by the end of the 19th century, with a flurry of consolidation work in the early 20th century.

Timing of such events can have uncertainty and for example the onset of the Younger Dryas is apparently 180 years later in Northern Europe than Greenland.

This was associated with the formation of various glacial lakes and influenced sea levels worldwide, which have risen since 22,000 years ago about 120 m (390 ft).

[9] Higher carbon content, as occurred after the lake reached sea level, causes greater deposition of iron sulfide, which appears as a black varve.

[11][a] The lake from the first evidence to the last has been dated historically in the range 16,000 to 10,500 years BP,[3][a] but there is now a defined end point at 11,620 cal.

[22] This was followed by a transitional phase called the initial Littorina Sea with partial salt water ingression commencing 9,800 cal.

[7] In the thousand-year period from 16,000  years BP the edge of the retreating Weichselian glacier departed from the Lake Gardno end-moraines of Pomerania (in present-day northern Poland) and reached the southern shore of the Baltic Sea where closed fresh-water pools formed in the southern Baltic region from melt water as the ice retreated northward.

The Baltic Ice Lake covered a large area by 13,000 BC between present southern Sweden, Lithuania and up to Estonia.

[9] By 12,000 years BP,[a] the edge of the glacier was at a line across southern Sweden to the northern shore of the Baltic countries.

A connected body of water, the Ramsay Sea, stretched from the Danish islands region to the shores of Estonia.

In the Allerød warm-period, rising land in the Denmark region ponded the lakes in the Baltic basin which may have egressed through a small channel in the Strait of Øresund or perhaps southern Sweden.

[9] At the peak of this high-water phase, most of Finland was under water, including present-day Helsinki at a depth of 115 m (377 ft); only southern Sweden was both free of ice and above the waterline.

years BP it broke through as a glacial lake outburst flood in a narrow corridor in the region of Mount Billingen in present-day south-west Sweden; from the 1920s Quaternary geologists used to describe the break-through as a massive, single tap of Niagara-like force, but there is now evidence that it happened in several steps over a limited period, and along different local troughs and passages, with evidence for all three of ice marginal, supraglacial, or subglacial drainage at various times.

[1] It has been postulated that because the ice cap had extended southwards during the Younger Dryas in south-west Sweden, a factor in the break through at Mount Billingen was that rebound was delayed there.

[1] At the start of drainage into the sea here the land was just a bit more than 25 m (82 ft) above the local sea level, and the drainage was both along the ice margin on the east side of Billingen and subglacially near present Timmersdala where recent interpretations are consistent with an ice tunnel existing.

[32] The ecology of the Bølling–Allerød Interstadial when the ice lake formed, has data from multiple northern European studies that may be relevant.

[36] The significance of the distribution of fresh and salt water species in working out the history of the Holocene Baltic lakes and seas was well understood by 1910.

[8] The Riadino-5 archaeological site on the lower Šešupė river in the Kaliningrad Oblast shows intraglacial human habitation with flint artefacts existed on the borders of the Baltic Basin between 50,000 and 44,000 years ago.

[37] Several carbon-dated sites in Estonia indicate that human habitation of the shores of the Baltic Basin was present in the Boreal period, in the time window 11,200-10,200  years BP.

Melt water formed extensive lacustrine systems still visible today in north Russia, Poland and Germany.

This area was referred to as an island in Greico-Roman literature as "Scandza" or less specifically as "Scandia", which is generally assumed to be an inadvertent misrepresentation by ancient geographers.

years BP,[1] the ice lake discharged as an outburst flood through channels that opened near Billingen in central Sweden until it reached the raising world ocean level.