Simplify the following text for a Grade 9 native English-speaking person.
Original: The territory consists of the main island , Tristan da Cunha ( area : 98 kmÂ , 38 sq mi ) , as well as several uninhabited islands : Inaccessible Island and the Nightingale Islands .
Simplified: The territory consists of the main island of Tristan da Cunha itself , which measures about 11.27 k across and has an area of 98 k , along with the uninhabited Nightingale Islands and the wildlife reserves of Inaccessible Island and Gough Island .