Double igloo with a treasure basement near spawn! The first igloo is located just a bit south from the initial point at coordinates 180 246, and the second one can be found up north at coordinates -222 -400.
As already mentioned, the first igloo has a secret chamber underneath with a chest inside. The second one is without the basement, but is located in a truly picturesque area.
Here's what you will find in the first igloo: