After the 1-Up
After the 1-Up mushroom placed on the broken sidewalk, there should be another broken sidewalk with the blue coin in plain sight.
After Using The Boat
Before getting off the boat, there are 9 blue coins placed around the sidewalk with the Rocket Nozzle box on it. You can use your boat to get all of these, however, it is fairly hard, and will probably not take you one try. Another method to getting these coins is using the Hover Nozzle to get to the desired blue coin, die, and repeat the process. To do this method, make sure you always grab the 1-Up placed on the broken sidewalk.
This needs to be integrated/expanded upon.
1)If you keep going along the path, there is a blue coin on a platform.
2)Using the boat, get to the end of the mountain, but don't crash it. Get all the outer coins first. Now, get all the coins in the inner area. If you crash at this point, that's OK. Just go to the platform. Hover-but don't jump-to the blue coins and then hover back.
3)Same as above.
4)Same as above.
5)Same as above.
6)Same as above.
7)Same as above.
8)Same as above.
9)Same as above.
10)Same as above.