The Kiwi Swim Club member spent five hours on five days swimming the 77km length of Lakes Hawea and Wanaka.
The windy first leg on Lake Hawea, and the choppy last leg into Roys Bay, Lake Wanaka, yesterday were the most difficult.
Meg (17) said she had spent a year preparing for the swim at Moana Pool in Dunedin.
She had not yet contemplated another long-distance swim.
The swim raised close to $5000 for the Otago-Southland branch of the Cancer Society.