Today this article is published in The Guardian, about recent finds under the floor of the chapel of St Athanasios, just outside the walls of the monastery. It looks like the bones they found are that small, that they have belonged to females.

“If a woman is found among the bones it will be the first known incident of a female finding her final resting place on Mount Athos,” said the architect restorer Phaidon Hadjiantoniou, who discovered the remains while conducting conservation at the chapel.
“There are times during pirate raids and hostile incursions that monks are known to have opened their doors to women but it is very rare,” he said. “There is a famous tale of a Serbian king who brought his wife to Athos but, throughout, she was carried and never allowed to step on Athonite soil. Carpets were placed in all the monastery rooms to ensure that even there she didn’t touch the ground.”

The bones are a secondary burial, so they have been moved from their original burial site. Dr Yannis Maniatis will conduct carbon dating to determine the date of death. This will give some answers about the time and maybe whereabouts of these bones. May they even date from classical/pre-Christian times, when Athos still was inhabited by Greek families?
Wim, 16/12 (thanks Gert Jan and Rolf Bos)
The simple explanation: she was a floater, drowned, and washed upon the athos shore… the monks gave her a decent burial?
See also my reply, and that of Bas Kamps, at post 2085.