Short answer: a day trip to Treasure Beach is a long way to go for a few hours on the sand. It is roughly two and a half to three hours by road from Montego Bay, Negril or Kingston, each way — so you are looking at five to six hours of driving for perhaps three or four hours actually here. It can be done, and some people do it, but it is not what this part of the coast is built for.
The honest math on drive time
Treasure Beach sits on the south coast, away from the airports and the resort strips, which is exactly what makes it feel different — and exactly why it takes a while to get to. From Montego Bay, plan on two and a half to three hours each way. From Negril, similar. From Kingston, also about two and a half to three hours, mostly on rural roads rather than highway. There is no fast route in from anywhere on the island.
What you can actually fit into a day
If you do come for the day, be realistic about what that buys you: lunch at one beach bar, a walk along Frenchman’s or Billy’s Bay, maybe twenty minutes in the water, and the drive back before dark. Floyd’s Pelican Bar or a Black River safari — the two best-known excursions from here — are both themselves half-day commitments, which does not leave room for much else once you have added the drive in and out.
Why staying over works so much better
Nearly everyone who visits Treasure Beach for a day says some version of the same thing afterward: they wished they had stayed. One night removes almost all of the pressure — you arrive without a clock running, see a sunset properly instead of from a moving car, and get a real morning here before the drive back. Two or three nights is where the area actually makes sense: enough time for one excursion, several unhurried beach days, and the slower pace that is the entire point of coming this far south.
If you are set on a day trip anyway
Leave as early as you can manage, accept that most of the day is driving, and pick one thing rather than a list — lunch and a beach, or Pelican Bar, not both. Build in slack for the roads, which are rural and slower than the map distance suggests. And if the day ends up being the best part of the trip, that is usually the sign to come back properly next time.