Complex sentence: Another campaign theme was the issue of oil drilling off the coast of the country within proximity of the Belize Barrier Reef after Belize started exporting oil in 2006; however, opinion polls showed opposition to further oil exploration.
Split into simpler sentences: Another campaign theme was the issue of oil drilling off the coast of the country within proximity of the Belize Barrier Reef after Belize started exporting oil in 2006. However, opinion polls showed opposition to further oil exploration.