Indonesia - it covers the Kalimantan part and has maximum geographical area (around 73%) of the island.
Malaysia - it covers the Sarawak and Sabah part of the Borneo Island with an area of about 26% of total area.
Brunei - Brunei is sovereign state, which covers the smallest area (i.e. 1%) on the north coast region.
The given map also gives other information about the Borneo Island including cities and other geographical features. By virtue of having the location on the equator, the island receives adequate rainfall and hence, it is lush with the flora. As per the study, it has more than 10,000 species of flowering plants. The maximum part of the island covers mountain and the highest peak is Mt. Kinabalu, which is measured 13, 435 ft. in Sabah region of Malaysia. Likewise, it is not only world's third largest island but also third highest island.