Using the GPX (select 'with no' or 'without geograph' option) export.
Get a text listing of squares - via the 'View list of nearby squares without images' link, on the "More Links for gridsquare" page.
Squares still showing Green on your personal coverage map (access it from the small map top right of your profile page)
Using the 'Personal Check sheets' - linked from the coverage map page [squares with photos are marked]
(Note: we only provide mapping indicating TPoint availability for a contemporary photo (taken now) - TPoints are also available for many historic photos)
Use the Recent Only Coverage map. Squares marked in Green OR Orange, can get a TPoint.
Squares with a PURPLE dot on the 'TPoint Availability' layer of the 'Draggable OS Map' (GB only)
Second/Third/Fourth Visitor Points
The 'Contributor Depth' layer of the 'Draggable OS Map' (GB only) shows the number of visitors to squares, so can spot the squares with 1,2 or 3 visitors.
The Find images by Square can find squares with only a given number of visitors. This example link shows for SP myriad, change the letters for other myriads. The listed squares only have 1,2 or 3 visitors. So 2nd/3rd/4th will still be available.