Caballo is an island in the entrance to the Philippines' Manila Bay. Caballo, along with the larger Corregidor (2 km to the north), separates the harbor entrance into a northern and southern channel. It is doubtful that Caballo measures even 5 km² in area.
... & Eton Central station[?]
Essex Road station[?]
Drayton Park station[?]
References
J. E. Connor, London's Disused Underground Stations, Capital Transport, ...