The Netherlands Roadblocks History
Season 4, Leg 5
In the Roadblock, one team member to get on a marked boat and using only their hands to catch 25 eels and put them in a marked container. Only the fisherman would get their next clue.
Season 12, Leg 2
In the Roadblock for this leg, one team member had to play a sport called fierljeppen by completing a single vault over a 12 feet (3.7 m) wide irrigation ditch and landing on both feet on the marshy grass at the other side.
Season 15, Leg 7
In this leg's Roadblock, one team member had to climb to the top of the Martinitoren and count all of the bells in the carillon. When they gave the right number (62) to the carillonneur, they would receive their next clue. If they provided the wrong number, they would have to climb back up to the carillon to count again. This Roadblock's hint is a reference to the first (aired) Roadblock ever on The Amazing Race.
I bet it's the season's 4 roadblock since season's 12 is WAY to easy co call "infamous" and season's 15 "secret answer" is no longer a secret