noun
sea and mountains; the great outdoors
Refers literally to the sea and mountains, often evoking nature, the outdoors, or a vast landscape. Can also imply a great quantity or variety, as in 海山の幸 (bounty of sea and mountains).
この地域は海山の幸に恵まれている。
This region is blessed with the bounty of sea and mountains.
休日は海山で過ごすのが好きだ。
I like spending my days off in the great outdoors.
noun which may take the genitive case particle 'no'
Used metaphorically to describe something as vast or deep, such as love, gratitude, or debt. Often appears in fixed expressions like 海山の恩 (immense obligation) or 海山の愛情 (deep affection).
彼には海山の恩がある。
I owe him an immense debt of gratitude.
海山の愛情を注いで育てられた。
I was raised with profound love.
山海 (さんかい) also means 'sea and mountains' but is more formal and often used in set phrases like 山海の珍味 (delicacies from sea and mountains). 海山 (うみやま) is more colloquial and can carry a metaphorical sense of immensity.
Compound of 海 (うみ, 'sea') and 山 (やま, 'mountain'). The metaphorical sense of 'immense' likely derives from the vastness of the sea and mountains.