Marine ecologist Robert Pitman observed a particularly dramatic example of this behavior back in 2009, while observing a pod of killer whales hunting a Weddell seal trapped on an ice floe off Antarctica. The orcas were able to successfully knock the seal off the ice, and just as they were closing in for the kill, a magnificent humpback whale suddenly rose up out of the water beneath the seal.
This was no mere accident. In order to better protect the seal, the whale placed it safely on its upturned belly to keep it out of the water. As the seal slipped down the whale's side, the humpback appeared to use its flippers to carefully help the seal back aboard. Finally, when the coast was clear, the seal was able to safely swim off to another, more secure ice float.