All the ships at sea,
instantaneously.

const ws = new WebSocket("wss://ais.openwaters.io/v1/stream");
ws.onopen = () =>
  ws.send(JSON.stringify({
    type: "subscribe",
    bbox: [[59, 10, 60, 11]]
  }));
ws.onmessage = ({ data }) => {
  const ev = JSON.parse(data);
  console.log(ev.mmsi, ev.msg_type, ev.lat, ev.lon);
};

import asyncio, json, websockets

URL = "wss://ais.openwaters.io/v1/stream"
SUB = {"type": "subscribe", "bbox": [[59, 10, 60, 11]]}

async def main():
    async with websockets.connect(URL) as ws:
        await ws.send(json.dumps(SUB))
        async for frame in ws:
            ev = json.loads(frame)
            print(ev["mmsi"], ev["msg_type"],
                  ev.get("lat"), ev.get("lon"))

asyncio.run(main())

url := "wss://ais.openwaters.io/v1/stream"
c, _, err := websocket.DefaultDialer.Dial(url, nil)
if err != nil {
	log.Fatal(err)
}
c.WriteJSON(map[string]any{
	"type": "subscribe",
	"bbox": [][]float64{{59, 10, 60, 11}},
})
for {
	var ev struct {
		MMSI    int     `json:"mmsi"`
		MsgType string  `json:"msg_type"`
		Lat     float64 `json:"lat"`
		Lon     float64 `json:"lon"`
	}
	if err := c.ReadJSON(&ev); err != nil {
		log.Fatal(err)
	}
	fmt.Println(ev.MMSI, ev.MsgType, ev.Lat, ev.Lon)
}

use futures_util::{SinkExt, StreamExt};
use tokio_tungstenite::{connect_async, tungstenite::Message};

#[tokio::main]
async fn main() {
    let url = "wss://ais.openwaters.io/v1/stream";
    let (mut ws, _) = connect_async(url).await.unwrap();
    let sub = r#"{"type":"subscribe","bbox":[[59,10,60,11]]}"#;
    ws.send(Message::text(sub)).await.unwrap();
    while let Some(Ok(msg)) = ws.next().await {
        let Message::Text(frame) = msg else { continue };
        let ev: serde_json::Value =
            serde_json::from_str(&frame).unwrap();
        println!("{} {} {} {}",
            ev["mmsi"], ev["msg_type"], ev["lat"], ev["lon"]);
    }
}

# live stream
SUB='{"type":"subscribe","bbox":[[59,10,60,11]]}'
echo "$SUB" | websocat -n wss://ais.openwaters.io/v1/stream

# snapshot of what is in the box right now
curl "https://ais.openwaters.io/v1/vessels?bbox=59,10,60,11"