It's a Bluesky link but he use adult tags as de facto "spoiler" tags. The problem is that content is hidden if you're not logged into Bluesky. Here's a Bluesky mirror site to show the entire thread...
https://subium.com/profile/c0nc0rdance.bsky.social/post/3kpkcq2ecws22
A huge hint...
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My first thought was
spoiler
the Bering strait thru the arctic, it kind of requires you wait 10 years or so but I think that's a pretty straight route
but now that I'm looking at it more
spoiler
Mercator projections are bullshit, Antarctica is really not that big, there's probably a nearly straight line crossing thru the antarctic ocean that misses the land by a bit