A bath could have an assortment of oils. A bath often had massage tables. A masseuse could rub down a patron of the bath with various oils. Scented oils are common. A pressure plate in an archway could trigger a shower of water mixed with a scented oil showering anyone who enters. Musk has a powerful smell. Anointing the party with the musk of some animal (or monster) could attract that creature with the intent to mate with the source of the scent. Floral and fruit based scents. The table below lists a variety of scents.
Bath toys can be a source of entertainment while bathing. Bath toys include ships. Imaging the party finding large sunken tub filled with water and an entire armada of wooden toy ships. The ships could include small figurine.
But, who could forget about the rubber ducky.