The Northern Kremisphere is a landmass presumably north of Donkey Kong Island. Its flora and fauna is a lot different from the usual jungle scenery and can be compared to the colder regions of Europe. It has woods, most notably Kremwood Forest, and has mountains with a lot of snow, and the climate is somewhat cold. The industrialization didn't help, either. Various different races of Kremlings, whose colours are more showy and eye-catching than Kremlings from other regions, made the place their homes.
Although it's cold, there's also jungles, and lakes that have brilliantly-coloured coral reefs and fish in lots of different colour. How would that be possible?
There's a volcano, referred to as 'Krematoa', that used to be sleeping until something triggered it to be active again. This implies there's a lot of volcanic activity around the Northern Kremisphere. This might also explain the jungles and the coral reefs. Regular lakes were warmed up thanks to underground magma, allowing coral to grow. This also goes for the jungles -- they're located on places where the magma provides an unnatural different climate, allowing them to flourish freely over certain places.
