Going green on the deep blue sea? Something like that — or at least as green as you can be while burning a bazillion tons of fossil fuels. Anyway, here's the story: Seems Royal Caribbean Cruises Ltd., parent company of Royal Caribbean International, Celebrity Cruises, Azamara Club Cruises, and a couple European brands, has been listed on the NASDAQ OMX CRD Global Sustainability Index, which NASDAQ's self-description says is "designed to track the performance of companies that are taking a leadership role in sustainability performance reporting. These companies have voluntarily disclosed their carbon footprint, energy usage, water consumption, hazardous and non-hazardous waste, employee safety, workforce diversity, management composition and community investing." The index includes just 100 companies, putting Royal Caribbean in rarified, uh, company.

In part, Royal Caribbean's reporting takes the form of its annual Stewardship Report, which tracks recent sustainability performance, progress, and activities related to its three U.S. brands. You can view the 2011 report here.