Help me understand this poem...?

It speaks metaphorically of the treacherous ocean waves as a woman who murdered (drowned) a child who was apparently lured into the water by its calmness (sheetings of silk, a smooth golden cloak), only to be overcome by the violent waves that followed (her bright locks were tangled....with one hand she strangled etc.) The last verse speaks of the murderess as attempting to wash away her bloodguilt. This is a morbid poem, very evocative and rich in metaphors.