A photomosaic approach developed by Dr Jon James (jonjames673@gmail.com) in collaboration with Sea Trust Wales (https://www.seatrust.org.uk/)

Welcome to Pwll y Môr!

What would you like to do?

Choose from the 'COME ROCKPOOLING' tab above!

About Pwll Y Môr

Pwll y Môr was created to help us survey Pembrokeshire’s rockpools remotely, allowing people to survey them from anywhere in the world! It also allows us to keep a detailed, long-term record of Pembrokeshire’s rockpools to monitor the effects of things such as climate change on our marine wildlife. Pwll y Môr was brought to life by Dr Jon James. Jon became interested in marine life, particularly shore life and rockpools, and had the idea of using photomosaics to record the rocky shore habitat. Pwll y Môr allows people to explore and learn more about our amazing rocky shore habitats from anywhere in the world. This increases accessibility to our coast, providing everyone with the opportunity to get involved. It's a brilliant way to learn and practice your species ID skills, whether you're a complete rockpooling beginner or a seasoned professional! The detailed rockpool photomosaics mean that we can identify and catalogue everything in the pool, which can be difficult when out in the field. This citizen science tool allows us to record our rocky shore biodiversity and investigate habitat changes over time. Pan and zoom across Pembrokeshire’s rockpools, identifying and cataloguing all of the species within.

What is a photomosaic?

A ‘photomosaic’ works by stitching together a number of individual overlapping photographs into one large image, allowing you to zoom in on the image and keep a high resolution. This means you can conduct a survey of rockpool wildlife in a high level of detail from your phone or computer. For Pwll y Môr, overlapping photographs of Pembrokeshire rockpools are stitched into a single high-resolution image which can be explored by zooming and panning.

Get Involved!

Survey Rock Pools

You can become a citizen scientist, virtually surveying Pembrokeshire’s rockpools. Click here to find out how to survey!

Take Photos

Or, you can take and submit your own photos of a Pembrokeshire rockpool. The Sea Trust team will then create a photomosaic, allowing other people to survey your rockpool! Find out more here.

Watch Educational Videos

Watch our Videos to learn more about Pwll y Môr and rockpool wildlife identification!

Select collection:

1. Hover over images to see feature and habitat notes.

2. Choose which to explore by clicking on its image.

Feature notes:

Habitat notes:

3. Choose an existing survey report, or start a new one (or just use the loaded default):

Survey summary:


Recorded species:


Upload the survey to the Pwll-y-mor server

Download the survey data as a .CSV file

How to & Help

Open the “Add/Remove Obs.” Tab.

Move the mouse onto the image. Zoom in or out using the navigation buttons in the top left corner, with a mouse, or with fingers if using a touch screen.
Pan using left-click and mouse or with fingers if using a touch screen.
Set to full screen mode using navigation buttons and reverse full screen mode using navigation button or the “Esc” key.
Pan and zoom the image to find specie of interest.
Start to type the common or scientific name in the "Search..." dialog box
Click on the appropriate entry from the list offered.
Double click on the species in the image - a symbol will appear.
Repeat for as many species/instances of species as required.
Select the “remove Obs.” Button and double click near an observation. To remove it.

Open the “Review Obs.” Tab.

Select the specie of interest from the offered buttons.
Repeatedly click the “Find” button to cycle through the observations of this specie.
As the specie is reviewed press the “Extra information” button to see additional specie information (if available).

Open the “Review/Save survey” tab.

Select the check boxes to see specie observations.
Press the “Save survey” button to save the survey to your local machine.
Press the “Download Survey” button to download the survey as a .csv file to your download folder.

Open the “Select image and Survey” tab.

The currently selected image is outlined in red.
Click on any of the images to change selection.

All enquires Jon James: 'jonjames673@gmail.com'

This website explores the use of photomosaics in habitat monitoring (recording and counting of species) and in the provision of resources for education and public out-reach.

The possible benefits of this approach are seen to be:

1. The combination of both detail and the broader context within a single image, for species monitoring and recording.

2. The provision of an immersive experience in which, for example, a rockpool can be 'explored' by the public, rather just passively viewed.


1. My son, Laurie James (laurie@lauriegames.me) for oversight and technical help and advice.

2. The staff of the wildlife charity 'SEA TRUST WALES' (https://www.seatrust.org.uk) for encouragement and ongoing collaboration.

3. The developers of the three, open source software packages on which this website is based:

i. 'Hugin - Panorama photo-stitcher' (https://hugin.sourceforge.io/)

ii. 'Deepzoom tools' (https://github.com/openzoom/deepzoom.py)

iii. 'OpenSeadragon - An open-source, web-based viewer for high-resolution zoomable images' (https://openseadragon.github.io/)

4. 'The Rock Pool Project' (https://www.therockpoolproject.co.uk/) and their local coordinator Bill Dixon for introducing me to surveying.

(All enquires Dr Jon James: 'jonjames673@gmail.com')

Submit Rockpool Photos

We are building a catalogue of Pembrokeshire’s rockpools. We can create photomosaics from your rockpool photos; these photomosaics can then be added to Pwll y Môr, for others to survey! Please read the below instructions carefully, and watch our instruction videos.

Rocky Shore Safety

Make sure to check the tide times before you set off rockpooling. The tide can come in quickly in Pembrokeshire and it’s easy to get cut off.

Wear suitable shoes. The rocky shore can be very slippery underfoot!

Watch your step! Be careful to avoid stepping on rocky shore creatures.

Do not use a net in rockpools. Hands cause much less damage!

Leave everything as you found it. If you move a rock - make sure to put it back as you found it.

How to take photos of the rockpool

  • Check out our video on how to take photos of the rockpool! (link)
  • Choose the rockpool that you would like to take photos of. The rockpool will need to have little to no glare from the sun; you can position your body to block the sun.
  • Note down the grid reference of your rockpool. This will provide us with an accurate location of your rockpool. OS Locate is a free app that can be downloaded on Apple or Android from the associated app store, which provides a grid reference for your location. Example grid reference: SM 860 137
  • Check your phone or camera to see if it has a grid feature. If it does, turn this on. This will help you to overlap your images. You are aiming for a 20% overlap to create a mosaic of your rockpool.
  • Position your camera around 3 feet away from the surface of the rockpool. Try to keep the camera vertical to the rockpool as any angle will create distortions and the image could be blurry.
  • To cover the whole rockpool it is best to start taking photos in the top left or right of the rockpool then move across the width of the rockpool making sure there is a 20% overlap. Then move down keeping a 20% overlap and repeat the actions in the opposite direction.
  • Keep your camera steady so the images are the highest resolution and can be studied.

How to submit your Rockpool Photos

  • Complete the Google Form with details of your rockpool → https://forms.gle/2Y9ocSHzEAv975Z4A
  • Follow the link to the Pwll y Môr folder → Pwll y Môr Photo Upload
  • Add a new folder by clicking “+ New”
  • Name the folder “your initials_date of upload”, E.g., “NT_06.06.24”. This means that we can match your photos with your Google form.
  • Upload your rockpool photos to the folder.
  • If you have taken photos of multiple rockpools on the same date, please complete a Google Form and create a new folder for EACH rockpool. Include - “rockpool 1” etc., in both the form and the folder name. E.g., “NT_0.6.06.24_rockpool1”, “NT_0.6.06.24_rockpool2”

The Sea Trust team will then process your photos and create a photomosaic to upload to Pwll y Môr. Not all photomosaics are successful. We will update you if we are unable to create the photomosaic, and give you some tips to work on!

Complete a Survey

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Species Guide

Top Tips

Have the Pwll y Môr ID Guide open alongside your Pwll y Môr survey so you can flick between both!

If you’re unsure about a species that you have identified, head to “Review Survey” and click “extra information” next to the Species ID. This will take you to MarLIN with more information about the species, helping you to check your ID and find out more!

https://www.marlin.ac.uk/ is a great website to have open alongside your survey. The “Species List” can really help with species identification.

Watch our Species ID videos to find out more and learn how to identify some of the common species found in Pembrokeshire's rockpools.

Pwll y Môr - Rockpool Species ID - Molluscs

Pwll y Môr - Rockpool Species ID - Anemones

Pwll y Môr - Rockpool Species ID - Breadcrumb Sponge

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