WARNING: This is not safe
You may have guessed but this is a genuinely dangerous thing to do. The website is written in a light-hearted fashion but you cannot overestimate the risks involved in taking part in this adventure.
Your chances of being seriously injured or dying as a result of taking part are high. Individuals who have taken part in previous Adventurists' adventures have been permanently disfigured, seriously disabled or lost their life.
This is not a glorified holiday. It's an unsupported adventure and so by its very nature extremely risky. You really are on your own and you really are putting both your health and life at risk. That's the whole point.