Millions of people in Puerto Rico need fuel, water, food and medicine. More than a week after Hurricane Maria devastated the island, major infrastructure is still down. Stores have trouble filling their shelves. Families are running low on the supplies they stockpiled before the storm, and across the island, many residents say they haven’t seen any aid deliveries.

Meanwhile, at the port in San Juan, row after row of refrigerated shipping containers sit humming. They’ve been there for days, goods locked away inside.

These containers were brought to the island by Crowley, a maritime shipping company. The company started unloading shipments on Saturday. By Friday, it will have received more than 4,000 loaded crates.

Most of the containers coming in have never left. Crowley says it has more than 3,400 commercial containers at its terminal now. That’s just one shipping company, at one port. Several other ports are accepting shipments, and stranded crates total an estimated 10,000.

“These containers are full of food, these containers are full of water, full of medicine … full of construction materials,” says Vice President Jose Ayala, who notes a barge a day has arrived since the port opened on Saturday. “It has reached Puerto Rico. The problem is we can’t get it on the shelves.”

Ayala says it’s frustrating: “People are out there under so much need, and there’s this cargo here.”

“Plenty of vessels can get cargo to the island,” agrees Mark Miller, Crowley’s vice president of communications. “But the real difficulty is getting the goods to the people via trucks.”

Meanwhile, hundreds of thousands of pounds have been delivered to the airport by commercial airlines, and the Department of Defense and FEMA have also been bringing in deliveries by air. Everybody — the government, aid groups and private firms — is having trouble moving those goods around.