Snorkeling Admirer

For our 10th anniversary my wife and I vacationed in Hawaii, where we went snorkeling. After an hour in the water everyone got back on the boat, except for one beautiful young woman and me. As I continued my underwater exploring, I noticed that everywhere I swam, she swam. I snorkeled for another 20 minutes. So did she. I climbed back in the boat. So did she. I felt very flattered and, as I took off my fins, asked her why she had stayed in the water for so long. "I'm the lifeguard," she replied matter-of-factly. "I couldn't get out until you did."