For this achievement, you need to fire one of your animals from the cannon onto the floating island. The easiest way to do this would be the flamingo and fly towards the floating island which is on the left-hand side of the map next to the football pitch. Once next to the cannon press y to get into it and aim at the middle of the tree and fire when the power is just below max. You should then hit the tree and land on the island which will get your achievement to pop.
If you need any more help I will leave my video guide below as well