Spring, or after a heavy rainfall, are the best times to visit the Fen, otherwise you risk doing a lot of "rock gardening" with your canoe or kayak.
There are two locations where you can put in. Munster Road, where you will paddle with the flow of the river, or at Joys Road, where you will be paddling against the current.
Also, putting in at Joys Road guarantees you will have to do at least one portage to gain access to the cache area.
NOTE: Due to the amount of heavy rain received in May 2017, a lot of debris has collected in one particular location (see reference waypoint), which is blocking passage.
You will have to portage around it until the river is cleared for the 2018 Jock River race.
Depending when you visit the area, the current can be very deceptive. When we visited on May 19th, 2017, a section of the river that appeared calm was actually carrying us along at approximately 4 km/h without putting a paddle in the water.
The cache has been placed so that it should avoid any issue with the high water levels in the spring, but also allow you to make the find without leaving your canoe/kayak (if you visit when the water levels are higher).
Congratulations to hopper12 and Mr.Packrat on the FTF