Bojnice's thermal spa uses natural mineral water from springs beneath the town, emerging at a comfortable temperature suitable for year-round outdoor bathing. The spa complex, known as the Bojnice Mineral Spa, offers indoor and outdoor pools, wellness treatments, and water slides, making it popular with Slovak families as well as foreign tourists combining the castle and spa in a single day.
The outdoor pools in summer, with views toward the castle's romantic towers, provide a pleasantly Central European atmosphere. The water's mineral content is believed to be therapeutic for joint and skin conditions, though the spa is enjoyable purely as a relaxation facility. The complex is a few minutes' walk from the castle; combined entry tickets are often available.