Introduced in preparation for Fortnite event Winterfest, Ice Boxes are located in several buildings on the island, sometimes replacing standard chests. Their exact drop rates had not been revealed by Epic Games, but player Fadefromthewrld has done his own research to find out your percentage chance of running into each fish when opening the container.
These figures remain approximate since Fadefromthewrld worked on a sample of just over 100 Ice Boxes. However, you can see that Ice Boxes are a very good way to obtain heals and shields.
So, if you're looking for a spawn that can provide you with large quantities of frozen fish, we recommend Mr. Polar's Artisanal Ice, which is located in Dirty Docks. You'll find a dozen or so coolers to rummage through.
Update 11.40 has not yet been officially announced by Epic Games. It should put an end to the Star Wars collaboration and perhaps to the snowy map of the winter festivities. Ice Boxes may also disappear with this upcoming patch.