Recycled rubber Merfin designed by Australian rubber manufacturer Mahina . currently , 37 , 000 are designing the first prototype of the monofin . The fin has an easy - fitting ankle strap and comes in adult and juvenile sizes . UK stockist says the fin has been ' very popular ' in recent months .
Recycled rubber Merfin designed by Australian freediver Kazzie Mahina . Mahina , 37 , spent years designing the first prototype of the monofin . The fin has an easy-release ankle strap and comes in adult and kid sizes . UK stockist says the product has been 'very popular ' in recent months .