Büchenau (Alte Allmend) is a calm quarry pond on the edge of Büchenau that suits relaxed freshwater diving and training sessions. The site is a simple shore-entry lake with shallow vegetated shelves, a marked entry area and deeper water toward the middle, so the dive is more about slow exploration than dramatic structure. Plan for permit rules, signed parking and modest visibility swings; pike, perch and carp are the main wildlife draw.