Swimming at John Beach is generally safe within the protected lagoon area, which offers calm, clear turquoise waters. The beach's remote location means there are no lifeguards, so exercise caution and never swim alone. Strong currents can occur outside the sheltered lagoon, particularly during changing tides. The white sand bottom provides good visibility of the water depth. Marine life is abundant, so avoid touching coral or unknown sea creatures. Always inform your boat operator of your plans and swimming abilities.

The optimal time is during calm weather conditions from October through May, when seas are most settled for boat access. Morning visits often provide the best lighting for photography and calmer waters. Tours typically operate based on weather and sea conditions rather than a fixed schedule. Visiting during weekdays can mean fewer tour groups, though the beach's remote location ensures it never feels overcrowded. Check weather forecasts several days in advance, as rough seas can cancel boat trips to Minamijima.