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.

In 1969, he took part in the crossing of the Caverna do Diabo with Michel Le Bret, J. L. Bret and Valla. He was elected President of the SBE in November 1973. In 1974 he founded the first underground laboratory in South America called LABSUB. He was then accredited by IPHAN for archaeological research in several regions of Brazil. He participated in several speleological expeditions in the State of Goiás and Bahia between 1971-1973, topographing the Mangabeira Cave in Bahia along with other Scientists, Lapa da Terra Ronca in Goias, São Matheus, São Vicente, Angélica, etc. He has authored numerous articles in magazines and the "Glossary of Speleological Terms", besides being a special lecturer at colleges, universities and conferences.