Uploaded October 2025 | Updated September 2026, 5 days ago
The man-made Ynys Ballast / Ballast Island was made in the late 1800s by the systemmatic dumping of stone ballast from ships returning to Porthmadog harbour. Sailing ships carrying slate to customers world-wide would return with whatever stone / gravel ballast they could find which had to be removed before the next trip. From 1862, the previous 'Rotton Tare' dumping area was full and a sand bank further down the river started to be used. The Lewis brothers, Joseph, John & Evan, built a wharf & commenced the bumping of ballast to form 'Lewis Island', nee Ballast Island. Eventually a steam crane was in use, together with tramways to distribute the ballast. Visiting the island today, it's striking to see the strange mix of stones from around the world.
The ownership of the island is apparently uncertain with the local council being encouraged to clarify this and ensure it's future as a historic landmark & potential nature reserve.
Further details:-
historypoints.org/index.php?page=cei-balast-artificial-island-porthmadog
portmm.org/the-museum/ballast-island
geocaching.com/geocache/GCT0D3
The man-made Ynys Ballast / Ballast Island was made in the late 1800s by the systemmatic dumping of stone ballast from ships returning to Porthmadog harbour. Sailing ships carrying slate to customers world-wide would return with whatever stone / gravel ballast they could find which had to be removed before the next trip. From 1862, the previous 'Rotton Tare' dumping area was full and a sand bank further down the river started to be used. The Lewis brothers, Joseph, John & Evan, built a wharf & commenced the bumping of ballast to form 'Lewis Island', nee Ballast Island. Eventually a steam crane was in use, together with tramways to distribute the ballast. Visiting the island today, it's striking to see the strange mix of stones from around the world.
The ownership of the island is apparently uncertain with the local council being encouraged to clarify this and ensure it's future as a historic landmark & potential nature reserve.
Further details:-
historypoints.org/index.php?page=cei-balast-artificial-island-porthmadog
portmm.org/the-museum/ballast-island
geocaching.com/geocache/GCT0D3
