Inimitably lightening up the Lagoon: La festa del Redentor

Another traditonal pilgrimage across the lagoon, from Venice to the Isle of Giudecca, takes place every year in July: On a ponton bridge, visitors can cross all the way from Zattere to Giudecca, to participate in the Festa del Redentor (here you can view the festivities program for 2012).

The Redentore feast began as a thanksgiving ceremony after the plague had ceased in Venice in 1576 killing more than 50,000 inhabitants. Doge Alvise I Mocenigo vowed to have a church built, and to return to this church once a year during the feast of redemption, as long as Venice would exist. Though there is no doge today, there is still the patriarch, who is leading the mass services held at the Redentore church:
A wooden bridge is laid to enable guests walk towards the Church of the Redentore from the Zattere. The bridge is made up of a modular system of wooden planks with railings, positioned on boats. In the same manner the ponton bridge is also used for the Festa della Salute, crossing the Canal Grande at Santa Maria del Giglio.
In this evening of the third Saturday of July, Venetians and visitors enjoy a delightful dinner, the Venetians on their private boats and vessels dotting the Bacino di San Marco, and the visitors taking in the view from the Riva degli Schiavoni. A special menu is served, traditionally it is duck (Petto d'anatra in peverada, for example).

And here comes a personal suggestion of mine: the best view visitors to Venice wishing to witness the fireworks can get is from the restaurant Harry's Dolci at Giudecca.
Walking across the Canale della Giudecca towards the Church
Click here for videos of the 2012 festivities.