The 100th runner home is awarded the obelisk in memory of Ted Ogden who was one of the founders of the event. The Challenge is his legacy and is now run by an enlarged team of organisers from whom further information may be obtained
7 years ago, I set 6 simple caches called the Otmoor Challenge 1 - 6 but now sadly none remain - This walk celebrates the Challenge in Olympic Year
Each of the Caches is named after a the Year and City where either a Summer or Winter Olympics has been held and also the ones that were cancelled in the 1940s.
Warning: Please be aware that some parts of this walk are only passable by wading - dogs and kids will need to swim for 11 months of the year. ...You have been warned!!
The boxes range from 2litre containers down to micro containers and many in between ... there isn't a hide that a novice wouldn't find- the challenge is to walk it and to enjoy the Otmoor and its surrounding villages.
NONE of the caches are accessible from the M40 even though Google will insist they are in the middle lane!!
Start anywhere you like but I recommend starting at number #1 in Charlton on Otmoor and walking away from the Otmoor leaving the extreme part of the walk till you are nearly home and dry. 
At least one of the caches has a high rating and you are advised to take heed and only try these if you are confident of your abilities. The Attributes where set to say no children are there for a reason - dont be stupid but enjoy your walking.