Algonquin Park is huge. There are many dozens of lakes, most of which have a few widely separated campsites on them. It is a good idea to contact the Park authorities several weeks in advance to ask them about camping conditions. It is an even better idea to ask them to send you a detailed map of Algonquin, and to laminate that map before you arrive. And this brings us to a very important topic.
Garbage bags work for clothing.
Bring plenty of rope to act as clothesline, just in case. Certain vital necessities which cannot stand water, such as toilet paper, should be double-bagged. Since it is absolutely impossible to avoid getting your feet wet, you should bring TWO pairs of shoes. The water in most of the lakes is perfectly drinkable once it has been boiled . Paddling is hard work, so bring large canteens which you can fill each morning with boiled water.