'beach-related' originates from English, specifically the word 'beach' (a shore of sand or pebbles) combined with 'related', the adjectival form of the verb 'relate'.

'beach' comes from Middle English 'beche' (shore, bank), and 'related' comes from Latin via Old French and Middle English ('relater' < Latin 'referre'/'relatus' sense of 'brought back' → 'relate'). The compound 'beach-related' is a modern English compound formed by combining the noun 'beach' with the past-participial adjective 'related'.

Initially 'beach' referred specifically to a shore or bank, and 'related' originally carried the sense 'brought back / connected'. Over time their combination came to mean simply 'connected to the beach' with no specialized historical sense.