As we watched, one emerged from the sea with seaweed in her beak to lay it onto a nest (above) right in the path and settle down; then the male emerged from the other end of the small peninsula on which we stood, carrying seaweed in his beak as well. She, sitting on the nest, squawked at him, and he, with his beak full, squawked right back as he waddled to the nest. He did his own nest building, and then they both settled down for a good joint squawking.
Views of the lava:
The skeleton (obviously neatly rearranged) of an unidentified whale is below left. The GPS marker for the Nazca Plate, on which most of the island ride, is below, and some intact sea urchin shells that we found and photographed (since beachcombing is forbidden) are below right.