This game is titled We Ski in North America and Europe, and Family Ski in Japan.
Ski past and go to the left of Owl Ski lift No. 6. Ski towards the wire fence, then side-step up a bank of snow. You will see a hole in the fence. Go through it and ski down the hill. Turn right sharply to find a hidden ice cave. You will exit out the other side at the bottom of the slopes.
Strategy guides from GameFAQs