Complex sentence: Economic hardship in Rabaul have produced violent gangs of "rascals" that prey on foreigners visiting aboard their yachts or by plane, reducing tourism to a trickle and further increasing lawlessness in the area.
Split into simpler sentences: Economic hardship in Rabaul have produced violent gangs, locally referred to as "rascals". These gangs prey on foreigners visiting by plane or aboard yachts, reducing tourism to a trickle and further increasing lawlessness in the area.