In the 1960’s, scientists discovered that Hudson Bay and the surrounding areas in Canada had less gravity than the rest of the world. They have always known that due to the shape of the Earth, an oblate spheroid, the gravity force would vary from place to place, but not like at Hudson Bay. To explain this anomaly, it is important to understand that gravity is proportional to mass so if there is less mass there will be less gravity.
This phenomenon has baffled scientist for many years, but they have eventually come up with two theories, convection drag and the melting of the Laurentide Ice Sheet. Convection drag is the forces created by the swirling magma that pull the continental plates down, decreasing their mass and therefore their gravity. The later is a more interesting phenomenon, as the Laurentide Ice Sheet that once covered most of Canada melted, it felt behind what is best described as a indent in the earth, which is slowly rebounding back (it will take another 5000 years) …. again less mass less gravity.
Now there is still gravity, so you won’t go floating around Hudson Bay, but you will weigh less!!