Granite Bay State Marine Park is located on the northwest corner of Esther Island about 25 miles from Whittier. This pristine park shows little evidence of human impact. The park includes two bays, protective islands, muskeg and old growth forest uplands. Most of the shoreline is steep granite cliffs, boulders and slabs. The surrounding hills provide excellent hiking and climbing with views in all directions. Many lakes and ponds dot the uplands. Tange Lake drains into the head of the northern arm and has been stocked with rainbow trout.

Anchorage is excellent in both bays and can be used by many boats at once. A mooring buoy is located between the bays, behind the islands. There are no suitable campsites. Two beaches of small pebbles, which are moderately exposed, afford camping spots during low tide cycles at the southern point of the mouth of the bay. A tent platform is located on the northernmost island at the mouth of the north bay. The platform on the northeast edge of the muskeg should be returned to standing position after use so as not to damage the vegetation. There are other tent sites on heather or in the beach grass. There is water at the head of each bay and from outlets from lakes. Boaters should be aware of a reef that extends nearly a mile offshore, just south of the mouth of the southern bay.

Activities
- Fishing
- Camping
- Hiking