When ocean accidents happen, submarine rescue often has much difficulty because of special environment of ocean and bad climate.
当海难事故发生时，由于海洋特殊的环境因素及恶劣的气候，此时的救援工作往往比较困难。
2
Ancient submarine forest grew in alluvial-pluvial deposit in Holocene Changle group, and the growing era is damp and hot climate environment as about 7000 ~ 7500 years ago;