Take a boat trip on the lake
The ticket office is located at the harbour, just past the pedestrian underpass. You can take trips to e.g. Meersburg, flower island Mainau, Ueberlingen, Friedrichshafen, Lindau, Bregenz, or down the Rhine to Stein am Rhein and Schaffhausen.
Swim
Either in the Rhine near the pedestrian bridge, or at the beach "Hörnle" at the east-most point of Konstanz. Bus 5 goes to the Hörnle. The Hörnle has a nudist area in German: "FKK" at its north end.
Konstanz Theatre
Konstanz has 3 theatres: "Stadttheater" for classic pieces, "Spiegelhalle" for youth theatre and experimental theatre, and "Werkstatt" for puppet theatre. You can buy tickets in advance at the Stadttheater Konzilstrasse 11 or at the tourist information centre inside the train station
Konstanz Philharmonic
You can buy tickets in advance at the Stadttheater Konzilstrasse 11 or at the tourist information centre inside the train station
Organ concerts at the Münster (Cathedral)
For schedules and pricing, see the website or contact the Münster music office at Pfalzgarten 4, or +49 7531 9062 52.
Festivals
International Bodensee Week
This festival is all about boats. It takes place in the spring 26-29 May 2011 and features boat exhibitions, regattas, and water skiing shows & competitions.
Rock am See
1-day music festival at the end of August 28 Aug 2011.
Carnival
This week-long event involves parades, costumes and parties. It takes place in the week preceding Ash Wednesday. Carnival is an old tradition in southern Germany, made up a mix of pagan and Christian beliefs, whose main purpose is to chase out winter. The secondary purpose is, of course, to dress up in a costume and party.
Konstanz Wine Festival
End of July 27-30 July 2011: An outdoor festival featuring local wines and live music.
Seenachtfest
1-day festival in mid-August 11 Aug 2011 with live music and other performances on a few different stages, water shows e.g. waterskiing, a market. The final event is a big fireworks competition between Konstanz, and neighbouring Swiss city Kreuzlingen. You can see the fireworks for free by watching in Kreuzlingen instead. Kreutzlingen also has a small midway and market during this event free entry.
Oktoberfest
The Konstanz Oktoberfest is rather smaller than the one in Munich but is worth attending if you're in town. It features the usual Oktoberfest-style beer, food, and live bands, and has a small midway. It takes place over 3 weekends: the last 2 weekends in September and the first weekend in October.
Christmas Market
An outdoor festival where the main marketplace and harbour are lined with stalls selling mulled wine, food, art and kitchy stuff. It goes for the 4 weekends before Christmas.