The departures are at 8 a.m. and 10 a.m. daily, but I suggest that your group be there at the time of the first departure because it is considerably less crowded.

considerably 是副词，由形容词 considerable（相当多的、可观的）加上副词后缀 -ly 构成。considerable 来自动词 consider（考虑），引申为"值得考虑的、重要的"，进而表示"相当大/多的"。 considerably 表示"相当地、显著地"，用来强调程度上的明显差异，这里指"明显不那么拥挤"。