Open Package From Diagram
As you develop your model, you might create diagrams that show the organization and/or content of some or all of the Packages in the model. From a Package element shown in one of these diagrams, you can quickly locate and expand the Package in the Browser window and open the Package default diagram in the Diagram View.
The default diagram is the first available diagram in the Package, selected in alphabetical order - for example, a diagram called Alpha in a child Package or element several levels down opens before a diagram called Beta immediately under the selected Package.
Double click on the Package.