Far Sight is a ridiculously busted ability. It doesn’t let you DO anything but you can SEE anywhere. You can clip against walls or floors and just go straight through them after a few clicks. You can go across continents and it never stops you - just starts doing quick 1s loading screens once you get out of range of yourself. You can see an unloaded world. You can see WIP areas outside of the play area of dungeons. You can see beneath the world. There’s a whole 'nother cave system floating like 1000 yards above Neltharion’s Lair (inside the instance). De Other Side has a completely trippy and flipped upside down… what looks like Nazmir from BfA on the outside. You can see that all with Far Sight.
And yet, if you try to Far Sight along the Sea Floor around the edges of the Eastern Kingdoms (and presumably elsewhere), it forcibly cancels the spell and returns you to yourself.
There is no endless pit from the short trip I CAN peek at - it’s just flat boring ground. I can actively get under the world. It lets me. But looking at the sea floor? The game says “No”.
So what doesn’t Blizzard want us to see?