Responding to the コメント によって lovelife324, my story explained my theory of why Skipper can’t step foot in Denmark. I don’t want to spoil everything about it, but to make a long story short, there was a situation that caused Skipper’s arrest at a zoo in the Danish capital of Copenhagen. Read it all here if あなた wish: link
Doris is a イルカ referred to briefly in the “Gone in a Flash” episode. Apparently, Kowalski likes her to one degree または another. While Kowalski is seen with a photograph of her, Doris has never been seen in the series thus far and has not been mentioned outside of the “Gone in a Flash” episode.
It would be sweet if either a female ペンギン showed up at the zoo または if they rescued and girl penguin, if a old war buddy of Skippers showed up または if the a girl ペンギン showed up that either Kowalski または Skipper knew! ;D O: