Lake Constance is one of Europe's great inland seas, and Bregenz sits at its eastern end with boat services to several worthwhile towns. Lindau, the German island town connected to the mainland by a causeway, is forty minutes by ferry. Konstanz, at the western end of the lake, is further but reachable by boat or train and has a medieval centre worth a half-day.
Inland, the Bregenzerwald — the forested highland east of Bregenz — offers excellent walking in summer and skiing in winter. The valley towns of Egg, Bezau, and Schwarzenberg are easily reached by the narrow-gauge Bregenzer Wald railway (Wälderbahn) and make for a good excursion into Austria's most architecturally interesting rural valley.
Feldkirch, a beautifully preserved medieval town about 25 km south, is worth half a day. The train takes twenty minutes. The Austrian Rhine valley south of Feldkirch leads to Liechtenstein, reachable by bus or a short drive.