IF you want to send arbitrary data. Usually people don't need that.
For something like coke smuggling you just need to know its on the way, get ready. So the OTP could be something as lame as "if you get a phone call from some rando who says 'Taste the Feeling'" then the next boat is full of coke, or if not, then the next boat is not full of coke". Actually terrible idea as taste the feeling was a coke company slogan a couple years back, but you get the general idea.
Most criminal activity involves communicating arbitrary data. Communicating that a drug boat is coming across a border is a tiny fraction of the communication in a criminal organization. In the scenario you described, planning out the communication protocol itself is an example of communicating arbitrary data... That needs to happen, at every physical hand-off point.
I had recently finished reading both books by Robert Mason, who started out flying helicopters for the Army in Vietnam and ended up smuggling literal tons of weed and got caught and did federal time. Pretty interesting autobiography. Anyway my comments fit pretty well with his description contained in his second book.
Mr Mason got caught by bad luck. There will always be small timers who do things small timer style who get caught by being verbose and oversharing, and to catch those we'll have "encrypted" smartphones.
You generally need more information flow than that to successfully coordinate a big logistics move like this though which is where you need arbitrary messages.
For something like coke smuggling you just need to know its on the way, get ready. So the OTP could be something as lame as "if you get a phone call from some rando who says 'Taste the Feeling'" then the next boat is full of coke, or if not, then the next boat is not full of coke". Actually terrible idea as taste the feeling was a coke company slogan a couple years back, but you get the general idea.