The Delavals (of Seaton Deleval Hall) were adept at exploiting their estate's resources such as sea salt, coal and glass. Their industriousness was matched by their approach to improving how these products could be more efficiently taken to markets by sea.
The harbour of Seaton Sluice was transformed by Sir Ralph Delaval between 1660 and l690 to satisfy an increasing demand for their coal. Stone walls were raised, piers were built at the north entrance to the harbour and an ingenious system of sluice gates installed. These enabled the tidal waves to scour the bottom of the channel to remove sand and silt that continually built up.
In 1764, brothers John and Thomas Hussey Delaval made further improvements by cutting a huge channel to link the harbour with the sea. The effect was to create a deep water dock allowing ships to be loaded with coal, glass and salt all year round and when the tide was out allowing more journeys (and profits!).