My partner is planning a surprise for me; but it can only take place on a sunday. What is it?

Okay, so it is only available on a Sunday, you need reservations, in Southwestern Ontario and is weather dependent. It was initially booked a month ago; but it has rained each available sunday since. I'm not very good with surprises and it has been driving me crazy trying to guess what it is. If you have any ideas please feel free to share them.