Flora and fauna
Bus from Otavalo or Ibarra to Cotacachi ($0,35), a town that specializes in leather goods, then a taxi to the laguna ($5)
Foreigners pay $1 to get in, Ecuadorians $0,5
Take the hike around the lagoon - 4,5 hours with some time to stop. Best done in a clockwise directions even though the signs all point the other way. Starts with an hour up a dirt road, 4km to "Las Pinas" then the real fun begins - basically traverses the rim of the crater and is an outstanding hike. There are two shelters at about the 2,5-3 hour mark going clockwise (earlier counterclockwise) that are useful if it starts raining. Possible camping spots are at either shelter or close to the start going clockwise.
There is a boat, $1,25 pp, but it rarely runs on weekdays as there aren't really that many tourists. You can of course pay for all the seats, or go on the weekend if you want to do this for sure.
A couple of vendors outside the main "La Muelle" complex
Expensive but quality restaurant at La Muelle ($6,5-7,2 entrees and $1,2 for a beer). There is another restaurant called El Mirador up the hill.