It costs 30,000g to go on your own per or 55,000g if you're bringing somebody with you per trip. It will take four hours to travel to Snowland, and you will return home at 9pm that same evening. You can unlock Snowland by visiting the Southern Island at least once and be in Summer of Year 1 or later.
When you hit the ice crystals with your hammer you can find Snowballs, Glass Stones, Elli Leaves, Crystals, Moon Stones, Old Coins, and Shiny Coins, or Ice. This is the only way to get Ice, which is needed to make a lot of dessert and cold drink recipes.
If you want to go fishing, you will need to get the Ice Drill to bore into the ice fishing spot. The plan for this tool is at Rebecca's shop for 800g You'll need 5 Rocks, 5 Silver, and 3 Rubies to make the Ice Drill. There looks to be two ice fishing spots, but only the one with the cracked ice can be drilled through.
Sweetfish, Salmon, Needlefish, Shishamo, Sea Bass, Large Sea Bass, Black Bass, Smelt, Angler Fish, Anchor Plan, Azure Fragment, Blue Stars Plan, Blue Pattern Plan
Elli Leaves, Pine Branch, Snowball, Thyme