Add Onwater API

README.md

@@ -278,6 +278,7 @@ API | Description | Auth | HTTPS | Link |
 | Mapzen Search | Open Source & Open Data Global Geocoding Service | `apiKey` | Yes | [Go!](https://mapzen.com/products/search/) |
 | Mexico | Mexico RESTful zip codes API | No | Yes | [Go!](https://github.com/IcaliaLabs/sepomex) |
 | One Map 2.0, Singapore| Singapore Land Authority REST API services for Singapore addresses  | `apiKey` | Yes | [Go!](https://docs.onemap.sg/) |
+| Onwater | Determine if a lat/lon is on water or land | `apiKey` | Yes | [Go!](https://onwater.io/) |
 | OpenCage | Forward and reverse geocoding using open data | No | Yes | [Go!](https://geocoder.opencagedata.com) |
 | OpenStreetMap | Navigation, geolocation and geographical data | `OAuth` | No | [Go!](http://wiki.openstreetmap.org/wiki/API) |
 | PostcodeData.nl | Provide geolocation data based on postcode for Dutch addresses | No | No | [Go!](http://api.postcodedata.nl/v1/postcode/?postcode=1211EP&streetnumber=60&ref=domeinnaam.nl&type=json) |