The choice of my equipment always depends on the type of dive I plan. At the same time, I try to keep the core elements of my setup as constant as possible. The bigger this constant part is, the safer I feel, and the safer my team is. Everyone must know their own kit so well that it feels like part of their body. It should be possible to operate every element almost automatically without long, conscious thinking.

My basic kit for deep, cold dives

•A drysuit with integrated boots and tight seals at neck and wrists so that no water can enter.
•Depending on water temperature, one or more undersuits plus a heated vest.
•Mask and fins that I know extremely well.

For almost 99 percent of my dives, I use a rebreather. This is a closed-circuit system. The exhaled breathing gas is not released into the water but flows back into a counterlung and then through a canister filled with soda lime. The lime binds the carbon dioxide from my exhalation so the CO₂ is removed from the breathing gas.

The most critical item of equipment is the dive computer. Technical divers usually carry at least two independent devices. The controller on my rebreather is my primary computer. As a backup I use another computer that should match the values of the primary device as closely as possible. This includes depth, total dive time, decompression obligation, stop depths and stop times. If the rebreather fails, I can still safely reach the surface with help of the backup computer and the bailout cylinders that I carry for emergencies.