Swelinia - [svɛ'ɭiːɲa], also known as Swelina or (in German)
Grenzfluß, is a name of a brook between Northern part of Sopot
and Southern Gdynia (Poland). Original slavic name Swelinia
occurred first time in documents from 13th century (Rivulum qui
Swelina dicitur, "a creek known as Swelina"), but subsequently
that name was not used in any official documents or maps until
it was mentioned again in the Geographic Dictionary of Kingdom
of Poland in 1888. The brook was always a border between Sopot
and other territories. The Treaty of Versailles specified it
(without mentioning its name, however), in the Section XI. and
article 100, as a border between Free City of Danzig and Poland.