The Senior's island is located at 8 degrees 1 minute West by 46 degrees North. This places it on the edge of the Bay of Biscay in the Atlantic Ocean.
Kim and Ron visited the Senior's island when Junior's tanning lamp drew so much power that it caused blackouts across Europe. It was at this time that Ron mentioned becoming a villain. Which Señor Senior, Senior took up as a hobby, and then threatened to attack Middleton.