A cargo worthy or seaworthy container is typically used for shipping purposes. A cargo worthy container is also wind & watertight (WWT). It will be free from holes and will not leak. However, once a container is retired from shipping service, the container needs to be re-certified by a maritime surveyor if it’s to be shipped again. To ship a container, it must conform to CSC (International Convention for Safe Containers) standards. It basically means that a container is suitable to be loaded/stacked on a container vessel for shipping. A maritime surveyor will ensure the container meets these standards. You should receive a certificate for the container that can be presented to the port authority. A cargo worthy container is generally 10+ years old. It will be in similar condition to a container that is WWT (dents, dings, surface rust, etc.).