Brennan has been diving for over 30 years and has made dives on 5 continents. His scuba experience includes recreational, technical (including trimix and cave), and scientific diving. Brennan is a military veteran with 25 years in the medical field. Brennan started his dive training while pursuing degrees in Marine Biology and Ichthyology in south Florida. He shares his passion for diving and science as a Public Health and Physical Education Adjunct Facility member at Hillsborough Community College.

Brennan is an Instructor Trainer for SDI, TDI, and RAID.  He is also a Course Director for NAUI.