Otters

Today when I was on my way back from the park, the sun was setting and I went out on the breakwater. When I was out on the breakwater, I saw an otter so I went out on the rocks and got out my camera. But by the time I had done that the otter had dove under the water. I waited out on the rocks for a bit, then I saw two otters farther out by the breakwater. I tried to get some photos of them but they went back into the water. I continued waiting out on the rocks. Then I heard one under the rocks I was on, and I looked down and saw one near me eating something. When I tried to take a photo of it, it saw me and when out of site. I could still hear it under the rocks. When I was still waiting, I heard one father up so I went to take a look. When I was standing on a rock looking around, I thought I heard an otter by me so I looked down. One of the otters was under the rock I was on. I tried to get a photo before it ran, but I didn’t get one. After a little while of chasing the otters around, I saw them in the harbor and one was near the breakwater. I could see the bubbles and it in the water when it dove, before it got out of site. After a bit more waiting I saw them near the boardwalk part of the way on the rocks and I got two fairly good photos of them there before I went back to get my gloves which I had left on a rock, and go home.
Why were the otters so hard to get photos of?
where did the third otter go?
what was the one otter eating?