I got it! 🙂
I was now able to dig moat from the sea to that promising 4th exit/entrance.
I got quite a lot of sand too. I digged a respecatble moat around the entrance and hauled a lot of sand all the way through my base to the furnace.
Only a few turns later I got a chance “to grab a fire”. A fireelemental had started a fire at a nearby tree. So I stepped forward, lit my wooden pole and tried to retreat back to my base. Yeah, the way back was closed. A nasty ghost stepped in my way and I had to run.
I chose to go quite a bit of the way around the mountain to reach my 4th entrance and made it. I reached the savety of my cave and hurried through my tunnels to go back to the first entrance where my furnace is located.
It was close… when I lit the furnace and a campfire and dropped the pole it had only about 80 turns left.
In the end it doesn´t matter that much. In no time I crafted TWO glass shards and made ONE solar still out of it which I positoned at the furnace and filled it with seawater form my moat at entrance 4.
Now I am able to eat meat and drink shallow water in masses. If I get poisoned I craft a healingwater and that´s it 🙂
From another fireelemental I got one more bottle. So I have 3 bottles, one working solar still and 4 Exits of which one has a really big moat.