Lighting up the sound - Tradução em português

What does that mean?

Here goes the full paragraph I noticed it in.

"We hadn't drunk that much liquor, had we? We thrashed through the dead palm branches and sea oats and walked on the beach again. The full moon shone like a floodlight, lighting up the sound. From the horizon just below the moon, a swath of shimmering sparkling flecks of moonlight swept across the water right up to the beach. The scene made us feel even more drunk, at least me, anyway. Franklin walked like a sailboat tacking against a head wind, as he zigzagged drunkenly back and forth." -- page 337, E-PRIME III! A Third Anthology, 1997.

Thank you.