The most unique feature is probably the emblem, of which Wikipedia says:
The emblem in the black is a boar’s tusk—the symbol of customs and tradition but also prosperity. Its worn as a pendant on the islands—along with two leaves of the local namele tree. These leaves are supposed to be a token of peace, and their 39 leaflets represent the original 39 members of the Parliament of Vanuatu.
Before independence, Vanuatu was a French-British condominium under the name New Hebrides, and under this god-awful flag, which fortunately seems to be limited to sporting events:
holy moly, that old flag… flags within a flag, what a disaster. I really like the new one, but think the leaves are too much detail