Somalia has largely been forgotten by the international community in its response to help victims of Sunday's tsunami, the United Nations says.
Beaches along East Africa were buffeted by huge waves
Jan Egeland, the UN's emergency relief co-ordinator, said UN personnel had only just reached villages affected.
Aid workers have described a scene of devastation on the Somali island of Hafun, a fishing community of 2,500.
The floods killed 120 in Somalia with 35 missing and some 50,000 displaced, its prime minister said on Thursday.
Displaced families on Hafun desperately need aid as they have no clean water, food, medicine or shelter as most of their homes and possession were swept away.
"Cases of diarrhoea and other diseases are already being reported," the UN's World Food Programme said in a statement.
The destruction of roads by the sea is hampering the delivery of aid and trucks loaded with 30 tons of food were stuck in sands 60km away from Hafun on Wednesday.
Twelve Hafun residents have been confirmed dead and many more are missing. Bodies can still be seen floating in the sea, Hafun's governor told aid workers.
The UN is planning an aerial assessment of Somalia's coastline on Thursday, where thousands of other people are reported to have lost their homes.
The newly elected Somali Prime Minister, Ali Mohammed Ghedi, is expected to arrive in Somalia on Friday to see for himself the devastation along the coast.
"The damage was felt all along the southern part of Somalia," Mr Ghedi, whose government is currently based in Kenya as the capital is considered too dangerous for ministers, told AFP news agency.
More than 130 people are known to have died in countries along the East African coast when waves swept 7,000km (4,000 miles) from the epicentre leaving a trail of smashed buildings and boats.
In Madagascar, more than 1,000 people were made homeless while a village in northern Mauritius was submerged for almost three hours following the surges.
The small Indian Ocean island of Diego Garcia - home to a US naval base - escaped unharmed as it was forewarned by the Pacific Tsunami Warning Centre in Hawaii.
Meanwhile, Mozambique - one of the world's poorest nations - has donated $100,000 to an aid appeal for victims of the tsunami.
Mozambique suffered from catastrophic floods four years ago, which displaced some 70,000 people.
According to the BBC's Jose Tembe in Maputo, the cabinet encouraged businesses and others to make donations to the country's Red Cross, which has set up two accounts - one for local currency and another for foreign currency - to receive funds.
The government described its donation as "symbolic", Associated Press news agency reports.