Two handwritten letters from Charles Self to Robinson, in the process of writing a book on behalf of the University of Bristol's Speleological Society. The first letter requests permission to use the boundaries of Robinson's Burren maps, upon which he has added cave and water tracing information. The second letter discusses how problematic the spelling of the names of caves can be, and agrees to help Robinson in marking caves in the revised map. (6-30 March 1980), 3pp;
Two handwritten letters from David Drew to Robinson, enclosing a photocopy of a map with Moher Néin marked on it (9 Jun - 14 Oct 1981) 4pp;
Letter from Peter Glanvill to Robinson enclosing photocopied articles about submarine caves that have been explored at Doolin. (21 Sep 1993) 6pp;
Two letters from Tony Boycott to Robinson enclosing a copy of his 1977 map with caves marked in. An index accompanies the map. A subsequent letter encloses a photocopied article 'Mysteries of the green holes' (15-21 Oct 1998) 8pp and 1 map;