The frantic effort to bring food, water and shelter to millions of Filipinos displaced by Typhoon Haiyan has been described, even by experienced relief workers, as a logistical nightmare.
Here are some of the obstacles facing aid agencies a week after the storm, as well as some of their priorities.
Philippines' island geography hampers aid delivery
The South Pacific nation is no stranger to destructive weather. But its island geography, and limited means of transport, means it is impossible to adequately prepare for the onslaught.
David Morley, the president and CEO of UNICEF Canada, said this is one of the times when military forces can be of huge assistance. "We need really big ships that are going to be able to get there because of the backlog in the airport," said Mr. Morley.
Grant Cassidy, World Vision's senior communications adviser who is currently in Cebu in the central Philippines, said difficulties are always faced when delivering relief after natural disasters but the humanitarian community usually has ways to get around them. "Here, in some places," he said, "you don't."
Relief workers fear many have yet to be reached
The storm has killed more than 4,400 people and displaced almost 1.9 million. But the true extent of the toll is unknown because some places have yet to be reached from the outside.
Stéphane Michaud, a senior operations manager at the Canadian Red Cross, said there were some areas, as late as Friday, that been assessed only by overflights.
Cat Carter, the head of humanitarian communications for Save the Children who is in Tacloban, said her agency is bringing a team of doctors into the country this weekend.
"They will be flying out to those different islands to make sure that the people on the islands are OK and to deliver medical assistance wherever possible," said Ms. Carter. "We are working around the clock to try to reach everyone that's been affected."
Fuel shortages delay humanitarian effort
Geoffrey Petkovich, the Asia Regional Director for ChildFund International who will be in the affected areas this weekend, said one of the biggest issues is the dwindling amount of fuel.
Gas stations have been levelled and much of the existing fuel was contaminated by the storm surge. Mr. Petkovich said that means gasoline is not available to relief workers who need it to power the trucks carrying supplies to hard-hit areas.
The fuel supply has also had an impact on the availability of clean water.
Ms. Carter said Tacloban's water is pumped mechanically from a mountain some distance away. "But they've only got enough fuel to last for another day and then it's going to have to be shut off completely," she said, "which means absolutely no water will be coming through to Tacloban at all."
Potable water is the most needed commodity
The most pressing need of the people displaced by the typhoon is water. That is true "hands down across a wide spectrum," said Mr. Petkovich.
"Potable water is a priceless commodity," he said, and even the relief workers are finding it difficult to get enough to meet their needs.
Mr. Morley said people are thirsty.
But the lack of water also means there is a lack of hygiene, which creates the threat if disease so there is a big push to create toilets, said Mr. Morley. That's not glamorous, he said but "it's very important."
Displaced seek shelter as rains continue
There are still three or four weeks left in the typhoon season. Even if there is no additional superstorm, it is constantly raining on people whose homes were blown away.
Mr. Petkovich said the mayor of hard-hit Ormoc, north of Tacloban, has told ChildFind there is a desperate need for tarps "to simply have something over their heads."
Ms. Carter said the displaced are living in little shacks made of plastic and wood. "When it rains – and it's raining pretty heavily here pretty much every day," she said, "there are so many gaps the kids start getting sick."