score:5
Ferries to the Toronto Islands run year-round. You'll just have to take a ferry to Ward Island and travel from there. It's a bit of a walk so I recommend to bring a bike. Shouldn't be a problem if you're physically fit and properly dressed for the weather. There's no taxi on the island, which is free from most motorised traffic.
Upvote:0
Since some links could be removed, I've simply typed the websites out for future research.
The torontoisland.com/ferry.php site has information regarding the seasonal schedules:
Winter service is to Ward's Island only starting 6:35am until 11pm. Check the ferry schedule online as boats do not run frequently during the winter.
Toronto.ca will have more details regarding which ferry points are open. Winter season ends on April 8, 2018. You can even buy your tickets online there.
Harbourfront Centre has info on water taxis:
TorontoBicycleTours.com will rent for various hours of the day or overnight, even up to 1 week.