If a baby is born on a cruise ship in the middle of the Pacific Ocean, it normally gets the nationality of its parents.

However, if it is born on a Canadian cruise ship, it also gets Canadian citizenship. This is somewhat unusual internationally, but it is the law in Canada. 

…all persons who were born on Canadian soil or a ship registered in Canada on or after 1 January 1947 acquired Canadian citizenship at birth

Canadian citizenship and immigration

The same applies if it is born on an Canadian airplane.

A baby born over the Pacific Ocean during a Canada-to-Japan flight could have grounds to become a Canadian citizen, no matter where her parents are from. Parentage will be the first factor in determining Canadian citizenship for baby Chloe, who was born in international territory.

Chloe was born mid-flight on an Air Canada aircraft heading to Tokyo from Calgary. Even if both the child's parents were from another country, they could apply to have her declared a Canadian citizen because the aircraft was registered in Canada.

Her mother said she had no idea she was pregnant. Oops!

It is quite easy to get Canadian citizenship by birth since the rules are quite loose compared to other countries. Anybody born in Canada, or Canadian territorial waters, or Canadian airspace, or on a Canadian ship, or on a Canadian airplane, even if by accident, gets Canadian citizenship.

Many people have Canadian citizenship and don’t know it. Just ask Ted Cruz about that.