To find this cache you must complete the 6 Marsh Mosh Multi caches.
Whilst completing the Marsh Mosh Multi caches you will have collected all the bonus numbers you require to find this extra cache.
Please do not go to the publish co-ords... it is wet and deep!
The cache can be found here:
N50 (T+X+X).(Y-V)(V+V-Y)3
E000 (Z+X+V).(Z-W)(W-V)0
For full description of the Marsh Mosh trails please see #1: http://coord.info/GC50KKF - The icons apply to all caches.