Systems, devices, and methods for providing weighted resistance to swimmers are provided. The device can be portable and easy to use and set-up. In one exemplary embodiment, a resistance training device includes opposed pulley modules having a rope disposed between one or more pulleys of each of the two modules, a weighted component associated with one end of the rope, an attachment mechanism for attaching the device to a substantially fixed location, and a user interface for associating another end of the rope with a user. In use, the device can be fixed to a substantially fixed location, such as a dive block, and can provide resistance based, at least in part, on the amount of weight associated with the weighted component disposed in the water. Other systems, devices, and methods are also provided.