Packing winds of more than 300 km/h, Cyclone Pam razed homes, smashed boats and destroyed crops as it struck late on Friday and into Saturday.
The official death toll was at eight with 20 people injured. But those numbers were almost certain to rise as rescuers reached the low-lying archipelago's outlying islands.
Witnesses described sea surges of up to eight meters and flooding throughout Port Vila after the category 5 cyclone hit.
Aid officials said the storm was comparable in strength to Typhoon Haiyan, which hit the Philippines in 2013 and killed more than 6,000 people, and looked set to be one of the worst natural disasters the Pacific region has ever experienced.
