I've had a few challenging deaths in my current play through, which is no-maps, no-portal.

I got stuck in a death loop in the mountains where I could almost make it out of the mountains without freezing, but not quite. I finally beat a few walls of my shack to get enough wood to make a hammer (luckily I had 2 stones) and destroyed my bed and the fire for one hail Mary attempt at getting down.

The plan was to get about half way and drop the fire. Warm up, and go the rest of the way. If I died, at least I would be out of the mountain and at spawn. I got half way down, dropped the fire, and proceeded to walk into it!

Fortunately my world has a huge spawn island, so I was able to make my way through multiple temporary bases and get back to my ship at the bottom of the island. I was able to use my ship to sail to my (at the time) main base, which was just across a channel, make some frost resist mead, and get my stuff back.

After that, in the swamps, I got over confident and died to a 2* draugr, but it was just after getting back from another adventure of getting lost, which is a long story... :-)

I hadn't set my spawn at my swamp base, so I ended up almost back at world spawn. I had to run for a couple of days through black forest in my underwear before I got back to my ship, which was near my swamp base. I sailed across, and was able to put on some old bronze armor and eventually, get my stuff back from the 2*.

Those are some of the best parts of the game IMO. If everything was smooth sailing, the game would be much more boring.