I loved engaging with different groups in the organization. I also participating in co-op activities and volunteering with events. The downtown office has several charity events you can support! In my role I was conducting business analysis; gathering requirements, stakeholdering, developing documents, etc.
As with any mature crown corporation (no longer), silos exist and things move slowly.
I think it largely varies by manager. My manager was a fantastic mentor, and is the largest reason I enjoyed my time at Hydro One.
Openness and welcoming atmosphere is directly correlated by number of co-ops in the group.
If you are in business, do not be afraid to ask to pursue opportunities outside of your normal work!