The park protects a remnant of the original native plant and animal communities once found along much of the mid north coast of NSW. It contains one of the largest and least disturbed areas of coastal (littoral) rainforest in NSW. The Sea Acres rainforest is of special importance as it is a sample of the maximum development and diversity of littoral rainforest possible at this latitude.
The species diversity of the Sea Acres subtropical rainforest is nearly double that of other coastal rainforest sites on the mid north coast of NSW. The park contains four vegetation communities of which rainforest is the dominant and most significant community:
- rainforest: subtropical, dry rainforest, littoral rainforest (Endangered Ecological Community)
- woodland: banksias and casuarinas
- grassland: themeda or kangaroo grass complex (Endangered Ecological Community)
- sclerophyll: species such as blackbutt and tallowood.
The reserve contains one of the largest and least modified remnants of the endangered littoral rainforest in NSW. The rainforest species diversity is nearly double that of other coastal rainforest sites surveyed in the area, with 172 rainforest species having been recorded.
Subtropical rainforest occurs along the creek and protected slopes and the moist easterly aspect of the valley. A dry rainforest association is found on the aspect of the coastal ridge between the beach and the creek.
Six plant species reach their southern limit in the reserve - coast cottonwood, Macleay laurel, necklace pod, golden ash, native wisteria, fairy’s slippers orchid and flat fork-fern.