Conversation so far:
When did Mary Shelley write Frankenstein?
Mary Wollstonecraft Shelley was an English novelist who wrote the Gothic novel Frankenstein; or, The Modern Prometheus (1818).
What did Mary Shelley have to do with Lake Geneva?
In May 1816, Mary Godwin, Percy Shelley, and their son travelled to Geneva with Claire Clairmont.

Question: what did they do while they were there?
Self-contained rewrite: what did Mary Shelley and her family do while they were at Lake Geneva?