HTO Park West is built on the eastern half of Maple Leaf Quay. The eastern portion was home to Canada Malting Company Silos - visible in the fog- until 1983. That portion was unused in the 1980s and 1990s.
HTO Park was designed by Janet Rosenberg. She is becoming one of the most prominent landscape architect in the city. The umbrellas were designed to evoke the Georges Seurat painting A Sunday Afternoon on the Island of La Grande Jatte.. This does not obviously work without people, in late October!
Water is right there, but there is no access, it is not recommended to swim there. First, you would have to jump about 2 meters down. I have never seen anyone jumping or swimming there, EVER! It would probably be on the news.
I have swam on the Toronto Island, but the water is very cold even in August.