Everything you need to know about finding sea glass at one of the world's most extraordinary beaches — from the best tides to the rarest colours.
Seaham is internationally recognised as one of the finest sea glass beaches on Earth. Unlike most beaches where sea glass is an occasional lucky find, at Seaham it carpets the shoreline — a living legacy of Victorian industry.
The reason is simple: for nearly 70 years, the Londonderry Bottle Works — once the largest bottle factory in Europe — tipped its daily waste glass directly into the North Sea. Over 150 years of tidal action has tumbled and frosted those millions of fragments into the jewel-like pieces collectors treasure today.
Most remarkable of all are Seaham's "end of day" pieces — swirling, multicoloured glass formed when workers swept the last coloured glass remnants together at the end of each shift. These pieces, with their marbled patterns and rich hues, exist nowhere else in the world.
Operated 1853–1921. Up to 20,000 hand-blown bottles produced daily. Waste glass was tipped into the sea each evening.
The powerful North Sea has smoothed and frosted the glass to perfection, creating those characteristic rounded edges and milky surfaces.
Multicoloured, swirled pieces made from mixed offcuts — the most prized finds and unique to Seaham. Increasingly rare.
The extraordinary history behind the glass.
In 1852, glassmaker John Candlish and business partner Robert Greenwell were granted a lease from the Marquis of Londonderry to build a bottle works on the cliff tops south of Seaham. The factory opened in 1853, initially producing black glass bottles.
Under Candlish — who went on to become Mayor and MP for Sunderland — the works expanded dramatically. At its peak, it was the largest bottle factory in Europe, with seven bottle houses employing hundreds of workers producing up to 20,000 hand-blown bottles every single day.
The factory also had its own chemical works, iron works, a private railway, and even a fleet of ships. Candlish built workers' housing, a chapel, a library, and a school on the site — a remarkably progressive Victorian employer.
At the end of every working day, waste glass — cullet, off-cuts, misfired bottles, end-of-shift scrapings — was tipped from the cliff directly into the North Sea. This practice continued for 70 years. The factory finally closed in 1921, its hand-crafting methods made uneconomical by the new era of machine-made bottles.
"Every evening, the glassworkers would sweep together the day's coloured offcuts — different batches of blue, green, amber, and clear — and tip them into the sea together. Those mixed, swirling pieces are what we now call 'end of day' glass. There is nothing else like them in the world."
— Sea glass collectors' lore, SeahamSeaham glass comes in a remarkable range of colours, each telling its own story of Victorian chemistry and craftsmanship.
The most characteristic colour. Multiple shades from pale aqua to deep teal — the colour of the Seaham sea itself.
Pale mint to deep emerald, from wine bottles and chemical jars. One of the most commonly found colours.
Rich warm tones from iron-containing glass batches, mostly from beer and medicine bottles.
Clear glass tumbled to a milky opacity. Beautifully smooth and satisfying to hold.
Pale blue glass, rare and prized. Often found as smaller fragments.
Deep, intense blue from cobalt chemical additions. A genuinely exciting find — do a little dance.
Warm golden tones. Yellow glass is particularly unusual — chemical sulphur produces this striking colour.
The holy grail for many collectors. Copper and gold compounds produce this extraordinary colour. Almost never found.
The jewel of Seaham. Swirling, marbled colours — green and amber, blue and white, every combination imaginable. Unique to this beach and increasingly rare.
The supply of sea glass at Seaham, while still extraordinary, is gradually diminishing as the historic stocks become exhausted over generations. Each visit to the beach is a little different — and that's part of the magic.
Timing your visit around the tides makes an enormous difference to how much glass you find.
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Around new and full moon, the tidal range is greatest — exposing more of the beach. These are your best days. Plan visits for these windows.
Arrive as the tide is ebbing (going out). This gives you maximum exposed beach before anyone else arrives to look.
Heavy swells churn up glass from the seabed that hasn't been seen in years. The day after a North Sea storm is golden.
Winter is peak season. The beach is quieter, storms are more frequent, and glass accumulates over the summer before you arrive.
Before other collectors, before the beach fills. Seaham attracts enthusiasts from across the UK and beyond — an early start is rewarded.
Glass concentrates in the strandline — the dark line of seaweed and debris left by the last high tide. Search here first.
The main sea glass beach, lying north of Seaham Harbour. This is where the majority of glass is found, making it the primary destination for collectors worldwide. Access is from the car park at the end of North Road (SR7 7AQ) or from the Seaham Hall Hotel grounds.
Look along the high-tide strandline, in clusters of pebbles, around small rock pools at the waterline, and wherever pebble ridges have formed. The glass is smaller than you might expect — take your time and look carefully.
South of Seaham Harbour at Nose's Point, Blast Beach sits on the site of the former Dawdon Colliery. More rugged and atmospheric, it produces glass finds too — especially after storms. The dramatic headland views are worth the walk alone.
Access from Nose's Point car park (off A182, SR7 7PT). This is also a double SSSI for geology and rare wildflowers — a remarkable place once one of the most polluted beaches in Europe.
Sea glass hides in plain sight. Give yourself 10–15 minutes to "tune in" — your brain learns to spot the characteristic frosted texture among the shiny pebbles. It gets easier as you go.
Bright sunshine reflects off everything — making sea glass harder to distinguish. A grey Durham sky provides flat, even light that makes frosted glass stand out beautifully.
The best angle to spot sea glass is low and looking along the beach — especially at the point where the tide is retreating. Crouch down and scan the strandline.
Don't just look for "glass-shaped" pieces. Many of the best finds are tiny or hidden. Turn pieces over. Multi-coloured glass often has muted colours on one side and vivid on the other.
The sea glass supply is finite and declining. Many collectors take only their favourite pieces. Leave some for the next visitor — and for the joy of the beach remaining as it is.
The beach is all pebbles and cobbles — not sand. Sturdy, grippy shoes or wellies are essential. In winter, waterproof layers are a must on the exposed Durham coast.
Check the tides, pick an early winter morning after a storm, and head to Seaham Hall Beach as the sea goes out.