Dalaran Island

Dalaran Island is an empty subzone of Dalaran that can be discovered by flying high above the city. It is not considered to be part of the no-fly zone.

Speculation
Dalaran Island is possibly an older version of Dalaran.

Dalaran Island seems like a vestigial leftover from a WotLK alpha build.

Dalaran Island may be another name for Cross Island.

Dalaran Island may be the rock that Dalaran proper is resting on.