Swimming is not advised due to frigid water temperatures of 4-9°C (39-48°F) year-round, which pose immediate hypothermia risk. The Beagle Channel's currents can be strong and unpredictable. No lifeguards or emergency services exist on this remote island. Isla Martillo is known for penguin colonies, and disturbing wildlife by entering the water near their habitat may violate protection regulations. Most visitors come specifically for wildlife observation from shore. If water entry is necessary, professional-grade thermal protection is required, and you should never swim alone in these extreme conditions.

The prime visiting season is austral summer (December-February) when temperatures reach 10-15°C with long daylight hours and calmer seas. This period coincides with penguin breeding season, offering exceptional wildlife viewing opportunities. November through March provides the best balance of weather and penguin activity. Tour operators run most frequently during these months. Winter (June-August) brings severe cold, limited daylight, and most penguin species migrate, making visits less rewarding. Weather-dependent boat services may have reduced schedules outside peak season. Always confirm penguin colony access rules with tour operators beforehand.