The definition of an Adventure Race varies depending upon who you talk to and what they’re doing at the time. However, most but not all Adventure Races involve paddling, the so-called Expedition Races pretty much always do and in these it is usual that the race organizer provides the boats for the teams.
The ITERA is no exception to this “rule”, and we are to be given a sit-on-top kayak, namely the feelfree Gemini for the 3 long paddle stages (110km in total).
Sit-on-tops are the most common choice for organisers, they’re less demanding and pretty much unsinkable but other options such as sea kayaks and open Canadian canoes can and often are used. Closed kayaks i.e. sea kayaks are less frequently specified as they fundamentally require a high level of skill and certification. The ITERA requires padders to be BCU 2* certified. You can study the BCU grading for England on the Canoe England web site.