The Galilee data set includes more than 131,500 (xi, yi, zi) triples where xi varies over about 12 km and yi varies over about 20 km. The water depth was measured using an Odom Echtrack DF3200 Echosounder, and the position of the boat at the time of the measurement was determined using a Motorola Miniranger system, which is composed of radio stations on shore and a recorder on the boat. Navigation was recorded using ``event marks'' rather than time, and no information on time is available. Although the precision of the acquisition system is high, there are some defects in the data caused by an occasional malfunction of the equipment. This creates artifacts in the final map, and makes processing of this dataset a challenging problem. Another source of artifacts in the model is the changing conditions of the acquisition, which create a strong footprint in the final map.