It will be very very difficult to reach Pico Duarte from Puerto Plata and back in one day. Figure it will take you at least three-1/2 hours to get to the first step of the shortest route to get to the Pico Duarte. This would be Puerto Plata-La Vega-Jarabacoa-Manabao-La Cienaga. From there it is about an 9-10 hour hike to get to the top of the 3,087 meter mountain, highest in the Caribbean. And then you would have to make the trek back. No way can you do it in a day. And you need to get permits at the La Cienaga stop, plus hire a guide, which is obligatory. Of course you can just make it to one of the points. The trip to the first stop of Los Tablones (about a two hour trek is gorgeous). Please note that the Pico Duarte climb is for the fit. There is always the option of contracting a mule, and it probably would not be a bad idea to hire a mule for your cargo and one for when you tire. These mules know the way of the road. On the other hand, if you are over 170 pounds, the mule may not care to carry you, so you should be prepared to walk. To do Pico Duarte on foot you need to be in very good shape, or have the vitality of a young kid.
To get to Pico Duarte check out in the Caribe Tours station in Puerto Plata if there is a direct bus to Jarabacoa. If not, take the one to Santiago and then catch the bus there to Jarabacoa. Once in Jarabacoa, you will have to take public transportation to get to La Cienaga. Ask at the bus station. The Caribe Tours bus rides to Jarabacoa are cheap -- guessestimate it would be under US$10, but the ride to La Cienaga can cost you twice than that or more, depending on who takes you there. Note you can overnight at the La Cienaga camp station for cheap. You should take your camping gear and make sure you bring some warm clothes because if you climb beyond 1,500 meters you will be feeling temperatures of under freezing point in the early morning.
I speak from experience. Made my first trip to Pico Duarte last October. Did most of the trip on foot, but believe I will shed my two big toenails because of the pressure of the trek downwards. It's an exhilarating trip, but my recommendation is that you take three days, or do not try to get to the top.
There are five main routes to get to the Pico. And you don't necessarily have to make it to the top. The Valle del Bao and the Valle del Tetero, two valleys on the way, get all the praise.
I believe though, that anyone who makes the trip to the Pico comes back changed. It is beautiful....
