Use the terrainenvironment around you to lead you to it.
Sand
Since shores are eroded, look at the earth beneath you and see if you can notice patterns such as increasing amounts of sand - quartz (silicon dioxide) and feldspar (sodium, calcium, and silica), which are in abundance near beaches, and increasing amounts of pebbles/worn down rock.
Some islands are made out of volcanic material, so increasing amounts of black sand (basalt) are also indicative of an oncoming island perimeter,
Elevation
Shores to be on a lower elevation, so if you see decreasing elevation, going downhill for a while would likely bring you to the shore.
Rivers
Rivers will also find their way to the shore, so if you see a river, follow it to the delta. However, a caveat - not all rivers will end at a large body of water. However, all rivers flow downhill, which is helpful since the shore will likely be at a lower elevation.
Animals
Some animals are just better at finding water, due to the raised humidity, the sound, the scents, etc. Other times, animals that have found water might signal to other animals that water is present. If you can identify those animals, you can follow them.
You can also use your own sense of smell. Saltwater can have a very strong scent, and you could use the wind to track where the scent is coming from. Another chemical, geosmin, is responsible for that pleasant earthly scent (petrichor) when the earth is disturbed by water. Humans are very sensitive to that smell (can detect it at as low as 5 parts per trillion).
Even if the ocean water doesn't cause that scent, rain does, and it rains more near coastal regions and where the wind hits high elevations from the ocean side.