Marc Grütter Instruktor Instructor OC-Advanced Trimix-Diver OC-Advanced-Nitrox-Open-Water-Diver OC-Cave-Introduce OC-Cavern OC-Deco-Diver OC-Extended Range-Diver OC-Full-Cave OC-Nitrox-Diver OC-Sidemount-Diver OW-Nitrox Diver