DNA tests revealed the remains found on Llanddwyn Island belonged to 57-year-old Avril Whitfield.
She was last seen leaving her Caernarfon home in April 2016.
Coroner Dewi Pritchard Jones recorded an open conclusion at the inquest into her death in Caernarfon.
The discovery of the foot was made in September at the island beauty spot.
"My experience of bodies in the sea, is even by September, it was almost certain the whole body wouldn't have been found," said the coroner for north-west Wales on Tuesday.
"The sea is very efficient in disposing of whatever is put into it."
The inquest heard it was likely the Mrs Whitfield entered the waters of the Menai Strait on the western side of Menai Bridge.
The coroner said matters could be revisited "if any further evidence comes to light" about Mrs Whitfield's death.
The body of a woman whose foot was found in an Ugg boot on an Anglesey beach is unlikely to be found, an inquest has heard.