National Geographic on Instagram: "Orcas are at it again. Earlier this month, three orcas were spotted off the coast of Lisbon, Portugal, swimming alongside a boat and ramming it so forcefully that it sank. It was towed back to shore and the crew on board was unharmed. This isn't the first time the behavior has been documented in the region, but scientists have new theories about why they do it. Learn more at the link in bio. Video by Mercedes-Benz Oceanic Lounge"