You will find this cache just before reaching another gate. You are looking for a ‘bison’ container, but not your average ‘bison.’ Sorry, but just a little more (summertime) hacking may be required. There is no need to remove the whole container, just unfasten the lower part.
After this it is just a few more metres and then it’s all downhill.
Congratulations go to Bottom Bracket for the First to Find