Pier 1 usually had ferries to and from Venezuela on a weekly basis, the last I knew. There are also private boats you can hire to go as well as small plane services (all legal). Before leaving and upon entering (whether to/from T&T or V'zuela) you are thoroughly searched, all of your belongings are emptied out and thoroughly inspected (custom officers take what they want), dogs are brought out to sniff through all luggage for drugs and whatnot, you must fill out your relevant forms and prove that you have your immunization shots (especially yellow fever) or receive one on the boat. With your traveling papers you must state how many days you wish to stay and once you are cleared, you can walk around and go where you please.
I would not recommend going though, especially now as corruption is on the rise. The safest trip might probably be via plane directly to Caracas and booking a hotel as close as possible to the embassy but even then you're taking a huge risk. Going through illegal or questionable means would just be asking for all kinds of trouble.
