Wave heights reached 15 to 18 feet at Lumahai Beach on Kauai's north shore, making it dangerous for everyone except those who who didn't know enough to stay back. This couple made a run for it to escape the whitewater that came in from behind them. Fortunately, they were looking at the time.
See the smooth sand at the edge of the shadow? That indicates that surf recently passed over the sand, even though it's not wet like the sand she is walking on. She is in the impact zone for the bigger waves in a set and, because she was watching, was able to scamper ashore. Never go up to where the sand is wet during high surf. That same wet spot can be knee or waist deep foam when the large waves appear. The biggest ones only hit every 10 minutes or so.
This local guy was watching the reef break at the far end of Lumahai, so he knew when to back pedal like an NFL cornerback. He knew what he was doing. If he stood that close in that same spot with his back turned posing for a picture, he would have been swept away. Numerous shoreline drownings occur in Hawaii along sloping-sand beaches with a near-shore break like Lumahai.