Viken
Neptun covers Viken (Sweden) through the SMHI network. One GET request returns its readings as JSON — in the same shape as every other network Neptun serves, so you write the parsing once.
Source: SMHI · Position: 56.1422, 12.5792
Request
curl -H "Authorization: Bearer mapi_YOUR_KEY" \
"https://neptun.marine-api.com/v1/levels?lat=56.1422&lon=12.5792&radius=5"