Lets Go Sledding!! is the 3rd level of the Tricky difficulty from the demo disk included with the Lemmings: The Official Companion strategy guide book.
Strategy[]
The easiest solution is to start by having the first Lemming dig at the start of the downward slope, which should leave a thin wall at the right. The second Lemming will escape, so make that one a Floater then max out the Release rate. When the floater lands, have it build into the snow pile to turn around, then again at the shore toward the cliff. About halfway through the second bridge, make the Digger into a Bomber to complete the path to the Exit portal.