Yes—with a realistic caveat. Urban outdoor furniture can absolutely use recycled ocean plastic, and recycled HDPE/PP recovered from coastal areas is already turned into benches, planters, bollards and picnic tables. The material is often processed into plastic lumber or moulded components, which suits outdoor use because it resists rot, moisture and insects.
The hard part is the “100%” claim. Ocean plastic is usually a mixed, contaminated feedstock: different polymers, salt, sand, fishing gear and colour variation. To make durable public furniture, producers must sort, wash, shred and compound it carefully, and they may need UV stabilisers, colourants or a small amount of virgin/recycled polymer to meet strength and safety standards. That means the final product may contain 100% recycled content, but it may not be made from 100% ocean plastic alone.
For a credible project, I would ask for third-party certification, a clear chain of custody, test data for impact, UV and weathering, and a take-back plan. So yes, it is feasible—especially for non-load-critical street furniture—but the claim should be verified, not just printed on a green label.