Collet began his speleological career in 1962. In 1964 he explored Gruta Casa de Pedra, where he first contacted Michel Le Bret and Pierre Martin. Collet and his friends traveled kilometers on the weekends to visit the caves in the route Caçapava–Iporanga. He topographed and explored the caves Pescaria, Chapéu, Gruta Casa de Pedra, Água Suja, Alambari, Arataca, Areias de Cima e de Baixo, Caverna de Santana, Gruta do Pierre, Bethary, Abismo da Paçoca and many others.