Dolphin Seen on an Apparently Healthy Swim in the East River A dolphin was spotted swimming in the East River off the East 90s of Manhattan on Wednesday morning and was still there Wednesday afternoon. Dolphins are occasional visitors to New York's waterways and, unlike in January, when an obviously ailing dolphin turned up in the filthy Gowanus Canal in Brooklyn, marine mammal rescuers did not immediately sound alarms. "I've been watching video of him swimming and he appears to be using a lot of water," said Kimberly Durham, rescue program director for the Riverhead Foundation, meaning that the dolphin was covering a lot of territory. But he intrigues me. The foundation's executive director, Robert DiGiovanni Jr., was en route to the scene on Wednesday afternoon and planned to do a health assessment of the animal, believed to be a bottlenose dolphin, Ms. Durham said. As of noon, the dolphin would swim in one direction for a couple of minutes, then turn around and swim back, remaining in the area roughly bounded by the East 90s of Manhattan, Randalls Island and the end of Astoria Boulevard in Queens. The Riverhead Foundation noted on its Facebook page: We have documented four occasions of reports of cetaceans in or near the East River since 2010. Three of those events were in February and March timeframe. In all four events, intervention was not deemed necessary and the animals did leave the area without further sighting reports. Dolphins usually travel in groups, though, and Ms. Durham added, "a bottlenose dolphin alone is definitely something that gives me a little bit of concern." The police, for their part, did not seem worried. "Just a dolphin swimming through," a spokesman said. It is not in distress and we did not aid it. He added, "Why would we pursue a dolphin?" Yana Paskova contributed reporting.