This is not write in the rain paper. We did look into that possibility but for this project the logistics was a nightmare and the cost was huge. We would also have to offer write in the rain pens or just use pencil.
We have taken our Field Journals on many hikes and outings all without damage to the paper. Big rain storms and all without ruining the pages or leather.
We do suggest that you not drop your Field Journal in the river unprotected though.
As long as you write in some sort of dry covering you will be fine. This is high quality durable paper that can handle a little moisture.