I suggest that you build a canoe and a paddle for the canoe and then travel to the land on the left side of the map. There are many apple trees there. Once you have revealed that land, you can put bridge blueprints down so that bots can build bridges there (since you can't carry a bot when you are in a canoe). You should use the canoe to reveal all of the hidden land on all the edges of the map.
You could cut down the apple trees to get the apples, but hitting the trees with the mallets will give you apples without losing the trees. If you cut down the apple trees you would have to dig holes and plant apples in the holes and wait for the apple trees to grow again. It's faster to just use the mallets.