Canon L WP are water proof and gas filled, Canon will not disclose if nitrogen or argon gas is used. All the other canon I S binoculars are not gas filled and only water resistant. Canon explains that water resistant does it mean water won’t get in , it just means the construction materials can withstand certain weather conditions. This is according to reputable knowledgeable sources at Canon.
I know for some waterproofing is very important and of course it’s a nice little insurance policy. Last week I got caught in a wall of water in the Florida Everglades raining down on me out of nowhere with my SF’s. But even when you’re not in the potential position to get a waterfall on you they are still extremely useful in cold and or damp humid conditions.