Sentence:  'But when the <WSD>surf</WSD> fell enough for the boats to get ashore, and Greening held a lantern for me to jump down into the passage, after we had got the side out of the tomb, the first thing the light fell on at the bottom was a white face turned skyward. 
Meaning of the word marked with <WSD> tags:  Waves that break on an ocean shoreline.