Complex sentence: In 2004 the penetrated depth was increased on each of three expeditions and for the first time the Ukrainian team cross the -2000 m mark for the first time in the history of Speleology.
Split into simpler sentences: In 2004 the penetrated depth was increased on each of three expeditions. At that point the Ukrainian team cross the -2000 m mark for the first time in the history of Speleology.