Canada's capital is an inland city.
Your choices are a driving due north to Hudson's Bay on the Arctic ocean.
Or due east into the Maritimes Provinces on the Atlantic ocean.
As for the "not on lakes" thing, why is that?
You do realize that the North America's 5 Great Lakes aren't typical lakes?
They're actually landlocked, freshwater inland seas.
The nearest of those to Ottawa is Lake Ontario.
It's 18,960 square kilometres in size and over 200 metres deep at its deepest point.
Full size freighters sail it:
Link - http://3.bp.blogspot.com/_27yaP5sJAYg/Su818EvB6gI/AAAAAAAABw8/rwQ72SKkkvY/s400/freighter-lake-ontario.jpg
Link - http://www.boldts.net/TorIh.shtml
And it's got beaches in abundance: http://upload.wikimedia.org/wikipedia/commons/d/d8/Lake_Ontario_-_Sandbanks_Provincial_Park_2001.jpg