Simplify the following text for a Grade 6 native English-speaking person.
Original: Also , Wellington is just across the Cook Strait from the South Island , it is close to the sources of abundant hydroelectric power that exist in that island . Excess electric power from the South Island is transmitted to the North Island via submarine cables laid across the bottom of the Cook Strait â '' directly to the Wellington area and the rest of its Island .
Simplified: South of Wellington is Cook Strait , the sea between the North Island and the South Island .