You could start the day by walking down to the fourth generation Kermoal Dominique Patisserie at the bottom of the hill.
Also at the bottom of the hill on the corner of the Place de la Mairie is the Ty Mad bar tabac which does good coffee with a great view over the canal.
There is a food market every Thursday morning 9.00-13.30 at the Quai Cosmao in Chateaulin.
Just up the road (a 5 minute drive) just outside Port Launay, there is an old farm which was left to two brothers, converted into a bar, an evening market and a live music venue, called Run ar Puns, it is very worthwhile tracking down. The organic and farmers market is on between 16.00-19.00 on Wednesdays. Browse the market and then pop into the bar for a drink and complimentary bowl of soup! They are very welcoming.
Port Launay has a (very small) outdoor market every Sunday morning between 9.00-13.00 at the Place de la Mairie.
There are plenty of restaurants and bars in Chateaulin. We can recommend Au Petit Bonheur bistro overlooking the canal. Very little English spoken, the menu is in French but they helpfully translated using Google Translate for us on a mobile phone and the food was delicious!
The coastal path of the Bay of Douarnenez is not to be missed any time of year. Dramatic and beautiful it is comparable to the South West coastal path.
The nearest beach is Pentrez plage, a stunning 4 kms long and wide sandy beach with a shop and eateries. Family friendly, it is supervised through the summer months.
Crozon beach is a drive away with more in regard to restaurants, cafes and bars. It has a more yachty feel and there is a surfers beach there also.
Of course, you could always take it easy at home, cook in the well-equipped kitchen, have a game of Petanque on the Boule court and enjoy a glass of wine taking in that view!
The River Aulne is part of the Nantes-Brest canal. The canal paths that run its length are great for walking, cycling and fishing.