If the road runs right alongside the sea/ocean, then you can call it an ocean road, like the famous Great Ocean Road in Australia.
You may also hear coastal highway/road. Highway is more common in American English. British say road/motorway.
It is a quiet, scenic road that follows the coastline with wonderful glimpses of sandy beaches and palm trees swaying endlessly in the summer breeze. Why not take the coast road to Santiago?
The three sentences you see above are great ways to describe a road that is along the coastline. In the first and second sentence you will see the words extend and stretch. Although these words do have a lot of different meanings in these two sentences they mean to go in a particular direction. I hope this explanation and these three sentences help you out!
A road that is next to the ocean is usually referred to as a "coastal highway" or a "road along the coast".
For example, you can say:
-I love driving along the coast.
-The coastal highway provides the best views in the city.
海沿いの道路は、通常「coastal highway」、または「road along the coast」と呼ばれます。
例えば、以下のように言えます：
I love driving along the coast.
（私は海岸沿いをドライブするのが大好きです。）
The coastal highway provides the best views in the city.
（海岸沿い道路は、最高の景色です。）
Coastal highway is the most common expression used in the US.
You can also say: I want to take a drive along the shore.
I want to take a drive on the coastal road.
Or you can say: Let's go for a cruise on the seaside drive.
coastal highwayが、アメリカで使われる最も一般的な表現です。
【例】
I want to take a drive along the shore.
（海沿いをドライブしたい）
I want to take a drive on the coastal road.
（海岸沿いの道路をドライブしたい）
Let's go for a cruise on the seaside drive.
（海沿いをゆっくりドライブしよう）
Coast is referring to where it is so on the coast ( near the ocean or sea)
A route is used to mean a way to get somewhere
A highway is a term used more in America, in the Uk we would say motorway/road instead
イギリス 
アメリカ合衆国 
南アフリカ 
