In a 1952 study, Wernher von Braun devised a "manned lunar lander" as illustrated below.
The study looked at three lunar landers taking a crew of 50 to Sinus Roris (Bay of Dew) in 1977. Sinus Roris "is a dark, basaltic plain on the near side of the Moon that forms an extension of the northern edge of Oceanus Procellarum".
Details concerning the Study state,
Each shuttle was assumed to have a turn-around time of ten days: three days to recover the lower stages and tow them by boat back to the Christmas Island launch center, and seven days for refurbishment, restacking, and fuelling with storable propellants for the next launch
My question is, which Christmas Island was being considered as a potential launch site?
Christmas Island, in the Indian Ocean, just south of Indonesia is an Australian territory. It has co-ordinates 10°29′24″S 105°37′39″E.
The other Christmas Island, spelt Kiritimati in Gilbertese, is part of Republic of Kiribati in the Western Pacific Ocean. Note, in Gilbertese, ti is pronounced as s, so Kiritimati is pronounced as Kirismas. It has co-ordinates 01°51′00″N 157°24′00″W. It used to be a British territory. The United Kingdom conducted nuclear tests there in the late 1950s and the USA in 1962.
Both are very close the equator, with the Pacific Ocean island being closer.