Lake/ rivers near Montreal

Go for a jet boat ride in the St. Lawrence River!

Central Montreal is an island surrounded by rivers, where the Ottawa River joins the St. Lawrence. Lots of water although not so many beaches close to downtown. The western suburb of Lachine, site of some of the earliest of the canals around the St. Lawrence rapids, has developed riverbank walks and recreation. It is easily accessible by public transit.

Hi Diane,
What follows is lengthy.
The cottage country that is the hours drive north of the city up to famed Mt Tremblant is all about relaxing by lakes. The area is comprised of the oldest mountains on earth, the Laurentians, aka les Laurentides. The actual Mt Tremblant village of promo fame is a faux-European ski village kinda place, touristy and maybe not so relaxing.

But if one veers into the surrounding countryside (e.g. La Conception) then the area becomes more of an unspoiled wonderland. 'Le P'tit Train du Nord' is the name for a former train line there that has been converted into a well-known bicycling trail perfect for your stated requirements.
The 'Bel Air' resort up there has an onsite service called 'Action Tremblant' where one could do as we did last fall---rent fatbike/ebikes to ride past local lakes such as Lac du Sommet (one picnic table by a beaver home) or the larger Lac Mercier. Bliss.
Satisfaction guaranteed.
And also a great sushi restaurant onsite!

PS Our recent TR here 'En Pays Quebecois' details all of the above plus some city hilites. We also recommend Beautys Diner, the William Gray hotel's terrace restaurant, Cardinal tearoom plus Premier Moisson bakery.
Good Luck.
I am done. The end.

Thanks so much. Will look into those areas