Pot-Boiler Lagoon: Critiques?

[barsoomcore]

So this is a simple island map for my DINO-PIRATES OF NINJA ISLAND setting. I started with a hand-drawn outline, scanned that and cleaned it up in Gimp, then used Create to add text, the "boiling water" graphic, scale and compass.

The idea is a collapsed volcanic caldera, where ongoing geothermal activity keeps the shallow lagoon waters near boiling, so the whole area is wreathed in steam clouds. There are Steam Drakes in the mountains, head-hunters who offer sacrifices (rowed across at great risk to The Altar, the nearest bit of land to the remains of the volcano ("The Black Cone")), the Steam Springs (possible source of steam-powered devices), and whatever the Roast Lobsters are.

Thoughts? I'm not happy with the "boiling water" effect, so any suggestions there would be helpful. I tried hand-drawing steam curlicues and it looked terrible. Any suggestions?