Katharinenhof Beach is known for its clear water, making it suitable for swimming, snorkeling, and diving, though the rocky-pebble shore requires appropriate footwear. Water shoes are essential for comfortable entry over the stones. The clarity of the water and underwater features attract snorkelers and divers interested in exploring Baltic Sea marine life. Swimming conditions depend on weather and wind, as with all Fehmarn beaches. There are typically no lifeguards at this hidden beach, so swimmers should be confident and cautious. The diving access suggests reasonable depth and interesting underwater topography, but always check local conditions and dive with proper equipment and experience.

For diving and snorkeling, visit Katharinenhof Beach from May through September when water temperatures are warmest and visibility is generally best. June through August offer the most comfortable conditions, with water temperatures reaching 17-20°C. For fewer crowds, opt for weekdays or shoulder season months like May and September. The beach's hidden nature and rocky-pebble surface mean it naturally attracts fewer visitors than sandy resort beaches, making it relatively quiet even during peak summer. Early mornings provide the calmest conditions for underwater activities and the most peaceful beach experience. Weather conditions significantly affect diving safety, so always check forecasts.