Came across the following situation:

Exploring the world by ship, I found the "Great Barrier Reef", 2 hexes off of a different continent. After some research, it appears the only way to work these tiles is with workers from a city.

Unfortunately, the "Reef" tiles are adjacent to two other civilizations and the "Cape Town" CS. One of the civs is attacking the CS. The Cape Town tiles seem to be the best location for a city, and Cape Town has asked for assistance against the attacking civ.

Are there any good options other than taking Cape Town?