Direct rail service from Rotterdam Centraal and Rotterdam Blaak takes about 15 minutes. there is direct service from Amsterdam Centraal via Den Haag and Rotterdam Centraal with the terminus in Dordrecht.
There is a fast ferry (waterbus) from Rotterdam. It's part of the public transport system and costs the same as the train.
Buses serve the city centre and local areas. A good way to see the city is to rent a bike from the bike shop next to the station. You'll need 50 euro in cash for the deposit for each bike.
The Onze-Lieve-Vrouwe-Kerk ('Our Dear Lady Church') or simply the Grote Kerk ('Great Church') was built between 1285 and 1470. The 65m tower contains a carillon with 67 bells including one weighing 9830kg, making it the heaviest bell in the Netherlands. Entry to the church is free. Climbing the tower costs one euro. Be sure you're in shape and not afraid of close spaces. The steps are steep and there is only one way up...or down. See the medieval clock works as well.
In the church see the brilliant stained glass windows and especially the modern window dedicated to the guilds of Dordrecht.
The Sliedrechtse Biesbosch, east of Dordrecht, and the Dordtse Biesbosch, south of Dordrecht, together form the Hollandse Biesbosch which is a part of the national park the Biesbosch, one of the largest national parks in the Netherlands and one of the last freshwater tide areas in Europe. The Dordtse Biesbosch has several recreational areas that are used for walking, rowing and swimming
Shopping in the centre of Dordrecht is centred around the Voorstraat, the Sarisgang and the Statenplein (Staten square). The Voorstraat is 1200m long, making it the longest shopping street in the Netherlands. Markets are held every Friday and Saturday on the Statenplein and in the Sarisgang and on Tuesday in Dubbeldam.
Many nice resturants are around the Statenplein and outdoor tables abound in good weather.
Scheffersplein off Wijnstraat (Wine Street) is also ringed with many restaurants and outdoor tables. Eet Cafe Baloe Beer is reasonably priced and tasty.
Broodje van Willem is a small reasonably priced sandwich shop at 433 West Voorstraat in the shadow of the Grote Kerk.