Mark Gosling updated Photos.
Nov 26, 2025Dive Spot Guide•
Cosmeston
Flooded quarry dive with shallow rock piles and weed.
4/5
2 dives by 1 diverScubaSnorkelShore EntryBeginner
LakeMuck
Booked freshwater quarry session with silty bottom, shallow structure and rain-sensitive visibility.
About Cosmeston
Cosmeston is a flooded quarry dive in a country-park setting that works best as a simple training or checkout site when visibility is holding up. Rock piles sit on a silty bottom, seasonal weed can thicken the route, and the whole place stays shallow enough for relaxed navigation. Plan for a booked session rather than a casual walk-in, because access needs notice and the fee is handled at the warden's office. Freshwater fish and eels are the main draw.
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Research + Early Community Signal At Cosmeston
Conservative research baseline blended with 2 logged dives by 1 diver.
VisibilityVisibility: 1m
AccessSimple entry
Marine LifeSome life
FacilitiesBasic facilities
CrowdedFew visitors
Current StrengthNo current
Surge StrengthFlat calm
Where Is Cosmeston?
This spotNearby spots
Community sourced coordinates.
Cosmeston Planning Details
Depth range, seasonality, and planning context.
Reported Depth
0m - 9m
Depth Note
The quarry is shallow, with a reported maximum depth of about 9m.
Best Season
Year-round, with drier weather giving the best odds of workable visibility.
Typical Conditions
Silty bottom with rock piles and seasonal weed growth; visibility may be poor after heavy rain.
Safety & Access At Cosmeston
Hazards, restrictions, and access requirements.
Key Hazards
Low visibilityRestricted access
Safety Notes
Expect visibility to drop after rain and keep close to the rock piles so orientation stays simple.
Access Restrictions
Book 24 hours ahead and treat the dive as a managed entry rather than a casual walk-in.
Legal Notes
Follow the park's booking and payment rules before entering the water.
Local Intel For Cosmeston
Community notes to help plan your visit.
Scuba
Best as a shallow quarry training dive with simple navigation around the rock piles.
Freedive
The shallow profile can be explored briefly, but the booking and visibility limits make scuba the clearer use case.
Snorkel
Snorkeling is possible in very calm conditions, but poor visibility after rain can make it underwhelming.
Cosmeston Dive Conditions Planner
Use the planner to scan this week, inspect today in local time, and understand how exposure shapes conditions at Cosmeston.
Current Snapshot
No data
🌥️Variable
Sunrise
No data
Time
No data
Sunset
No data
Surface / Entry
Wind No data · Tide No data
Sea State
Swell No data · Period unavailable
Visibility Outlook
Rain chance No data
Wind
No data
Swell
No data
Exposure Profile at Cosmeston
Directional shelter context for incoming swell.
Exposure Note
Hourly forecast data is not available yet.
Wildlife at Cosmeston
Species commonly reported at this site, with direct links into their wildlife guides.
Recent Logged Visits At Cosmeston
2 community dive logs and visit reports for this site.
M
11/2/2025 at 10:12 AM (Europe/London)
Scuba Diving
★★★★★
3/5 OverallMax Depth:8m
Bottom Time:37 min
Water Temp:11°C
Conditions
CurrentNo current
SurgeFlat calm
Detailed Ratings
AccessEasy entry
Marine LifeSome life
FacilitiesBasic facilities
CrowdedFew visitors
Review
“Diveplace: Cosmeston (Wales, Penarth). Visibility: Bad. Water: Fresh. Entry: Shore. Divesuit: Drysuit. Computer: Shearwater Petrel. Start pres 170 bar, end pres 100 bar. Deco: No.”
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M
10/12/2025 at 08:45 AM (Europe/London)
Scuba Diving
★★★★★
5/5 OverallMax Depth:8m
Bottom Time:22 min
Visibility:1m
Detailed Ratings
AccessEasy entry
Marine LifeSome life
FacilitiesBasic facilities
CrowdedVery quiet
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Dive Spot Log Averages At Cosmeston
Average conditions based on logged dives & visits.
Conditions
Avg. Visibility1m
Avg. Water Temp11°C
Avg. Max Depth8m
Activity
Avg. Bottom Time30 min
Total Logs2
Unique Divers1
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Cosmeston Guide - Frequently Asked Questions
Planning answers for access, conditions, timing, and site logistics.
Cosmeston Guide - Sources and Updates
Last Updated
Recent community updates
Research Sources
aquaparkgroup.co.uk · Official Document
Official lake-activity page says the lakebed was scuba-surveyed and water depth is suitable.
www.valeofglamorgan.gov.uk · Official Document
Official fee schedule confirms dive charges for Cosmeston Lakes.
www.valeofglamorgan.gov.uk · Official News
Council article confirms the eastern lake is an active managed water-activity site.
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