This achievement is story related and cannot be missed.
This achievement can be earned in the fourth world "Sea of Serendipity" on the first level "Port O' Panic." On the 2nd stage of the level you will see Annetta trapped by a Darktoon who will flee from you. You will then have to chase down the enemy while dodging cannons from a far off ship, falling napalm, and water mines. After the chase the Darktoon will jump into a small body of water, merely follow and attack it to free the Nymph. You will be awarded a special ability and 15G!