A sea wall protecting the Maldives capital, Male, prevented half the city from being destroyed by the December tsunami, the United Nations says.
Some islands suffered serious devastation
Its representative in the Maldives, Mohamed Latheef, said that while the city was flooded, the wall saved properties from being badly damaged.
UN Secretary General Kofi Annan ended a 24-hour visit to the islands on Monday to see the devastation for himself.
More than 80 people were killed by the waves in the Maldives archipelago.
"The impact was less important because of the wall," said Mr Latheef.
"We couldn't avoid having Male flooded. But without the wall, half of Male would have been totally destroyed. Male didn't sustain any major destruction of properties," he said.
Officials say there were no fatalities in Male - home to a quarter of the overall population - because the capital's concrete 3.5-metre sea wall stopped the waves.
Mr Latheef said he wanted to extend the sea walls to build a "necklace" around the islands.
But that will be expensive - experts say it will cost around $4,000 a metre.
Mr Annan visited two islands in the south of the archipelago where many inhabitants were made homeless.
The BBC's Barnaby Phillips on the island of Kolhufusi says that he met a community in shock. Local people say the entire island was covered in water, and hundreds of people were thrown into the ocean.
Our correspondent says Mr Annan walked along the beach to see houses and fruit trees that were swept away.
Mr Annan praised the 'community spirit' of the Maldives
He saw the tents where people are sheltering and met groups of children who are receiving counselling.
"I am surprised by the strong community spirit and sense of voluntarism among the islanders," Mr Annan said.
"In the two islands I visited today, I saw how people from one island were helping the other after the tsunami left many homeless. This shows much promise for Maldives' recovery and reconstruction efforts."
Our correspondent says that locals were encouraged by the visit.
Although the death toll in the Maldives was relatively low compared to other countries, the economic infrastructure has been badly damaged and experts say reconstruction will not be straightforward because of the logistical challenges presented by the vast archipelago of tiny islands.
The government says that the impact of the tsunami has set back development by two decades, with 53 of the country's 199 inhabited islands suffering severe damage, while about 20 were "totally destroyed".
Nineteen of the country's 87 luxury resorts were severely damaged and will be closed for many months.