Lake Thun and Interlaken

Before the Dive

• Confirm current local entry and exit permission, closure status, ship lanes and weather with an active operator. Historical club site descriptions are not authorization.
• Use appropriate cold-water and drysuit skills, tested equipment, conservative gas reserves and an altitude-aware freshwater computer configuration. Dive within your current certification and practiced experience, not just a stated site maximum.
• Establish a buddy, a land contact, site-specific surface signaling and the location of emergency oxygen and communications.
• Keep away from boat approaches at Fischbalmen/Beatenbucht and other traffic zones; follow local marking and dive-flag rules.
• Recheck Gunten Bad bathing-season dive prohibition. Club sources disagree about the September/October reopening date. Do not infer permission from a calendar alone.

During and After the Dive

• Watch for cold stress, low visibility, disorientation and unexpected drop-offs. End dives early if conditions or equipment are unsuitable.
• Never attempt spring/cave penetration or technical decompression dives without the necessary training, permits, team and rescue capability.
• Avoid immediate mountain ascent, flights or strenuous high-altitude excursions after compressed-gas dives until appropriate decompression guidance is satisfied.
• Freedivers must never dive alone or hyperventilate; a qualified dedicated safety buddy and appropriate protocols are essential. Surface swimmers stay in marked safe zones.

Urgent illness, diving injury or suspected decompression illness requires immediate Swiss ambulance activation on 144 (or 112). Inform the dispatcher about compressed-gas diving, dive profile, altitude and any neurologic symptoms; follow their advice about oxygen and transport. Rega can be reached at 1414 for Swiss air rescue where appropriate. The Interlaken/Unterseen area has hospital emergency services, but a general emergency department is not the same as a verified on-site hyperbaric chamber. Specialist hyperbaric care exists elsewhere in Switzerland, such as Geneva University Hospitals, and clinical dispatch determines the suitable destination. Verify insurance coverage for dive injury, chamber care, helicopter evacuation, search and rescue and repatriation. Do not rely on a general travel policy or Rega support for automatic payment. Emergency numbers are listed by Switzerland Tourism.

Canton Bern protects sensitive reedbeds, fish habitats and waterbirds along the lakes. At the Weissenau-Neuhaus nature reserve, do not enter the water, bathe, boat, fish from shore or leave marked paths. These explicit reserve restrictions override the regional tourism rule that bathing is normally allowed unless signed otherwise. Maintain neutral buoyancy near sedimented walls, avoid touching or collecting wildlife and plants, do not feed fish, and respect nesting habitat and managed shore entrances. Clean and thoroughly dry equipment before moving between different lakes to limit invasive species. Canton Bern imposes reporting and cleaning requirements for boats changing between specified water-body systems, including separate Lake Thun and Lake Brienz groups; the boat-specific law should not be presented as a universal statutory requirement on scuba gear. References: Canton Bern protected-area rules and vessel cleaning law.