Once you are ready to reach one of the highest levels in Technical Diving the TDI Advanced Trimix or PADI Trimix course will teach you how to proficiently conduct dives up to 330ft/100m. One of the challenges taught in this course is the use of Trimix mixes with oxygen levels too low to be adequate for use on the surface. You will also learn how to plan for deep gas switches and the use of support personnel.
This course requires 4 decompression dives with a minimum of 100 minutes total bottom time. Two of these dives should be deeper than 230ft/70m. Although the TDI and PADI courses are similar, there are some differences in standards/prerequisites. Prior to starting you can choose which course you want to follow and which certification card to receive.