The harbor in Friedrichshafen contains a ferry landing for the so-called "Lake Constance Ferry" located at the Bodensee (Lake Constance), Baden-Württemberg, Germany.
The Lake Constance ferry, which can beside cars also be used by pedestrians and cyclists, runs between Friedrichshafen and Romanshorn all year every hour. The ferry operation is jointly operated by the Lake Constance Schiffsbetriebe GmbH and SBS Marine AG.
Between Friedrichshafen and Romanshorn the ferry almost cross the deepest part of Lake Constance (about 254 meters below the lake level). And you can also save around 70 kilometers of road - that is nothing else that connect the useful (no traffic jam, a warm cup of coffee, a light breeze in your face ...) to the practical.
source: [DE] BSB