Phnom Penh is about 133 km from the ocean.
If you're driving to a town near the beach or coastline, you could try Kep.
How far is Idaho Falls from the ocean
How far is Des Moines from the ocean
How far is Mesa from the ocean
How far is Monterey from the ocean
How far is Salem from the ocean
How far is Pasadena from the ocean
How far is Richmond from the ocean
How far is Grand Rapids from the ocean
How far is Mystic from the ocean
How far is Fez from the ocean