Energy is used when you dig or search in an island. You cannot dig or search without energy.
You start with 100 energy and gain 1 maximum energy per level achieved.
One energy point is recovered per five minutes.
Use fruits to recover energy or ask friends to send some. You may also use an energy pack to completely refill your energy bar once every 24 hours.
Be careful though as there is currently a glitch with asking friends for an energy pack. If you attempt to dig without having enough energy, it may ask you if you want to ask your friends for an energy pack. If you click 'Cancel', you will not be able to ask for an energy pack for 24 hours.