The province is bordered by Ilocos Sur to the north, Benguet to the east, Pangasinan to the south and to the west by the shores of the South China Sea (West Philippine Sea).
Ang Marinduque ay umagapay mula sa apat na sulok: North, South, Northeast at Southwest ng Tayabas Bay, Sibuyan Sea, Mompov Bay at Tayabas Strait, ayon sa pagkakabanggit.