A humpback whale was spotted swimming in the naval port of Den Helder on Monday, SOS Dolfijn said on Twitter. "The animal shows normal behavior, so leave it alone for now is the current advice", the sanctuary for whales in the North Sea said.

SOS Dolfijn expects that the whale will leave the harbor by itself.

Humpback whales are a relatively common sight along the Dutch coast. In January one was spotted off the coast of Egmond, according to the Telegraaf. In January last year one was seen near Hoek van Holland and a month earlier another was spotted off the Zeeland coast. 

Sinds vanochtend zwemt er een bultrug in de Marinehaven. Het dier toont normaal gedrag dus met rust laten is nu het advies. pic.twitter.com/sNboH9yMAg

— SOSDolfijn (@SOSDolfijn) February 27, 2017

We hebben een bultrug op bezoek bij de Marine. Welkom!#denhelder #bultrug #defensie #waarneming pic.twitter.com/9kFb0yAfuU

— MarineGV (@MarineGVtweets) February 27, 2017