A "wild breaker" likely refers to a cresting failure (
). What happens is a vessel rides the crest of a wave; but, if the vessel is overloaded, the boat's ends that are left out of the water take on the full, out-of-water weight and the hull becomes damaged.
The Northumbria was a single-hulled tanker, meaning that if the hull was damaged, there was nothing to keep her cargo from spilling out. This was a design flaw that came with scaling up a smaller vessel without additional reinforcements. Spills and cracks became a recurring damage that the Northumbria suffered in its short career. The black guts are crude oil. I'm not sure about the "ocean of flame." There isn't easy access to any record of any of her spills actually catching fire, so I take this line to refer to her dumpster fire of a career.