Untersee (Lake Constance)
Basin of Lake Constance
The Untersee (German pronunciation: [ˈʊntɐzeː], lit. 'Lower Lake'), also known as Lower Lake Constance, is the smaller of the two lakes that together form Lake Constance. The boundary between Switzerland and Germany runs through it. The lake surrounds several islands, the largest being Reichenau Island.
Geography
The Lower Lake Constance measures 63 km2 (24 sq mi) and is situated about 30 cm (12 in) lower than the Obersee. The Romans called it Lacus Acronius. In the Middle Ages, the Upper Lake was called Bodamicus Lacus, or Bodensee in German. At some point in time, this term began to include the Lower Lake, and a new term "Upper Lake" (in German: Obersee), was introduced for the larger lake.
The main tributaries are the Seerhein and Radolfzeller Aach. The source of the latter is the Aachtopf, a karst spring whose waters mainly derive from the Danube Sinkhole, making the Danube indirectly a tributary of Untersee and the Rhine, respectively.
The landscape surrounding the Untersee is very diverse.
“Untersee (Lake Constance)” enters the record as basin of Lake Constance. Crown Archives preserves that source wording while asking what Untersee, Lake and Constance can confirm, complicate or overturn.
Why this record matters
“Untersee (Lake Constance)” is worth following because a concise public description often conceals a longer documentary argument. Here, Untersee, Lake and Constance provides the most credible route into that argument.
Maps, plans, fabric surveys and administrative records can establish how the site’s name, extent and function changed over time. The source revision retrieved here is dated Sep 25, 2026. The linked authority identifier is Q565637. VIAF identifies the subject as 235135588. Authority coordinates are 47.683, 9.000. 2 of 2 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank.
Modern boundaries and familiar names can conceal earlier jurisdictions or structures that do not align with the present site. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Treat names, boundaries and functions as historically changeable. Maps, plans, inventories and administrative records can clarify what the place meant at different dates.
- Historic place names
- Jurisdictional context
- Routes into maps and plans
Contemporary maps, plans, listed-building records, estate papers and the responsible local or national archive.
Three-step research path
- Establish the record: confirm the title “Untersee (Lake Constance)”, its source revision and the description used here.
- Expand the search: follow Untersee (Lake Constance) primary sources, Untersee (Lake Constance) archive and Untersee research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Untersee (Lake Constance)”?
- Which authority defined the place, boundary or structure at the relevant date?
- Which earlier names or jurisdictions may reveal additional records?
Search terms from this dossier
This entry incorporates text from “Untersee (Lake Constance)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.