Like many islands in the Lagoon, this little island just off San Pietro di Castello originally hosted monks (Augustinians in 1199, then the Carthusians that gave the island its name), until Napoleon came and made it into a fort. Afterwards the island was abandoned.
Original plans for its revival into a park in 2010 suffered a set back when it was hit by a rare tornado in 2012 when many of its trees were damaged. At the time of writing, it has a modest three-star hotel, the Certosa Marina, Venice Kayak, a company offering a variety of guided tours around the city and lagoon, and a sailboat, available for hire or tours with Venezia in Vela.
vaporetto: lines 4.1 and 4.2 (request stop)
Image by Venice Kayak