Key communities:
content providers/media
education
funders
NGOs
commercial interests
federal agencies
key decision makers
public?

Identify key players within the community and target them first

Start with the panache!

Sign up the leaders within each stakeholder community

Sign up the associations/groups that have collections of stakeholders
e.g.:
education - NSTA, COSEE, Woods Hole, AZA (Assoc Zoos Aquariums)
research - OOI

Who owns and manages DO?

Explore existing models: wikipedia, internet archive, ...

This essentially comes down to what is the sustainable funding model, which will define ownership. Possibilities:
foundation support (not viable long term)
advertising/sponsorship
user fees (uggh)
embed in a core institution (university, government, ocean NGO, ...)
basic service free, premium service charge
events + schwag

media - National Geo, Discovery, ...