It measures approximately 150 kms. It is approximately 40 kms at its widest point. Borongan, the capital, is the largest municipality in terms of area. The largest island is Homonhon in Guiuan with approximate land area of 105 sq. The interior part of the province is rough and hilly and covered with dense tropical vegetation but drained by numerous rivers and creeks.
Mountain ranges and peaks abound in an interior.
The highest among them located at the northwestern part of the province is at 783 meters above sea level. Narrow plains hug most of the coastal areas and in some instances the banks of its principal rivers and their tributaries. Most of the coastal twons are located on narrow deltaic plains. The widest contiguous plain on relatively level ground lies west of the poblacion of Dolores near the southern banks of the Dolores River. Another smaller plain is located at the municipality of Quinapondan.