on Survivor 9/28/06 what was the killer two-step challenge?

Question

Survivor

Answer 1

You had to basically carry a 15lb. sandbag in knee-deep water and chase the other tribe doing the same (in a circular oval). If you wanted to drop out, you had to give someone your 15lb. sandbag.

The first person of either tribe to tackle one of the opposing tribe members wins immunity. The blue team won when Yul (red Aitu tribe) was tackled.