Standard and Poor's raises RCL outlook to 'positive'

'BB' is S&P's highest non-investment-grade rating.

S&P expects a variety of Royal Caribbean metrics to improve by the end of 2015 as a result of meaningful revenue and EBITDA growth from the addition of the Quantum-class ships along with general macroeconomic improvement.

The ratings agency said improved credit measures could position Royal Caribbean for a one-notch higher rating.