The whale, estimated at 18 metres (59 feet) long, beached itself yesterday morning at Popoyo beach, in the town of Tola, some 111 kilometres south of the capital, according to the Environment Ministry's delegate in the region, Mario Rodriguez.
More than 50 people - from Nicaragua and elsewhere - spent the day trying to get the whale back into deeper waters, but gave up in exhaustion as the sun went down.
The Pacific region off Nicaragua's southern coast sees a lot of humpback whales and dolphins at this time of year.