These surf crawlers mine for gold offshore in the surf zone. They can be productive and profitable as long as they are operating. They are limited by high wave action and bad weather but can stay out longer than the small suction dredges that are usually mounted on modified pontoon boats.

Notice how the spacer piece is added between the excavator and the tracks? This gets him out of the water and lets him transit out into deeper water (when the waves are down). However, this space takes away from his reach and limits how deep he can dig. The “house” on the back is adjacent to the sluice that separates the gold from the dirt he digs up. It is a slow process heading home.