After you have defeated the Boss in level 4 and earned the bazooka, return to level 1, Arctic Antics. Shoot the three woolly mammoths to get extra lives.
Once you defeat the second Boss and have the "Double Jump", jump on the heads of the woolly mammoths (you do not have to wait for the bazooka). You will get an extra life for each woolly mammoth you jump on. Note: For the one at the end, you can get up the glaciers if you keep trying.
Go to the bonus platform and go through the bonus level. When you get back, jump to the right. You should hit a woolly mammoth and get one extra life if you jumped on it. You have to jump back quickly because the woolly mammoth vanishes
