海蚀，为海水对于海岸线陆地的侵蚀，所形成的一种作用。一般的海蚀通常伴随着潮汐，周期性的潮汐引起海水向陆地的水平流动，进而对陆地边缘产生侵蚀作用，而其中又以波浪的侵蚀力最大，前冲的波浪进入陆地，而后退的波浪挟带砂砾磨蚀海岸，通常海蚀发生在岩岸地形较多，海岸的岩壁受到海水作用，外侧的岩体被海浪切断，进而剥落而形成。海蚀侵袭的海岸通常会形成一种特有的海岸线地形，一般常见的如：海崖、海蚀凹璧、波蚀棚、海蚀洞、海蚀门、海蚀柱、海蚀平台，如遇地形抬升还会形成海阶等海岸地形。

Coastal erosion is the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, drainage or high winds (see also beach evolution). Waves, generated by storms, wind, or fast moving motor craft, cause coastal erosion, which may take the form of long-term losses of sediment and rocks, or merely the temporary redistribution of coastal sediments; erosion in one location may result in accretion nearby. The study of erosion and sediment redistribution is called 'coastal morphodynamics'. It may be caused by hydraulic action, abrasion, impact and corrosion.