Olivier Isler, a Swiss cave explorer, created a unique lightweight rebreather called Hydrophilis, designed for easy swimming underwater. This device is lightweight, allows for 1.5 hours of operation, and features a chest-mounted design to reduce the risk of a dangerous condition called Immersion Pulmonary Edema. The Hydrophilis combines innovative hydrodynamics, using a specially shaped helmet and efficient breathing system, to enhance diving experiences. After 36 dives, Isler finds it enjoyable, though there are still improvements to be made for efficiency and performance.