We publish a dataset that comprises horse movement. Data was collected during a study with nine Warmblood horses walking on a water treadmill at five incremental speeds. Horses were measured under two conditions: on the water treadmill with water at mid-cannon bone depth and on the water treadmill without water (dry treadmill). The order of the two conditions was randomized. In both conditions, the baseline speed was set at 3.4 km/h, which was increased four times with steps of 0.2 km/h resulting in 5 speeds: 3.4, 3.6, 3.8, 4.0 and 4.2 km/h. Horses were walked at each speed segment until enough strides were collected (the aim was 30 strides), or for a maximum of 60 seconds. Data were collected with inertial measurement units (IMUs) at 200Hz. Head, trunk and sacrum vertical displacements, limb timing and limb sagittal angles were measured. The locations can be found in the readme file.