Ocean conditions API and MCP server for AI agents

KaiCast answers "how's the water?" for a place and a date — water visibility, swell, wind, tide and water temperature, plus where and which day to dive, snorkel, freedive or spearfish. It is one API with two doors: a REST API and a remote MCP server that drops into Claude, ChatGPT, Cursor, VS Code or your own agent.

Under the hood KaiCast is an ocean-conditions model: it fuses NOAA buoys and tides, PacIOOS ocean models, Open-Meteo Marine and satellite ocean-color data into a water-visibility forecast that is checked nightly against divers' logged observations. It is the same engine behind the KaiCast app.

Location is a parameter everywhere — ask about any coordinates on Earth. Where KaiCast has calibrated data, you get numbers; where it doesn't, you get an explicit not_covered answer with the nearest covered spot, never a guess. Coverage grows region by region (see Coverage).

There are two layers:

Layer	What it answers	Price
Facts	"What are conditions at this spot, these days?" — visibility, swell, wind, tide, water temperature, a 0–100 condition score, per 3-hour period.	Free, no key
Decisions	"Where should I snorkel tomorrow?" "Which day this week is best for diving at Hanauma Bay?" — ranked picks with why, confidence and caveats, plus a branded KaiCast spot card.	Free during early access

Both layers are available two ways, with identical answers:

REST API at https://kaicast.com/api/v1/… — described by /openapi.json. See REST API.
MCP server at https://kaicast.com/mcp — four tools for any MCP client. See MCP server.

Quickstart #

Facts — one spot, the next few days:

bash

curl "https://kaicast.com/api/v1/conditions?spot=hanauma-bay&from=2026-10-06&to=2026-10-08"

Decision — the best snorkel spots on Oʻahu tomorrow:

bash

curl "https://kaicast.com/api/v1/recommendations?region=us-hi-oahu&activity=snorkel&date=2026-10-06"

Decision — the best day this week to dive near a point:

bash

curl "https://kaicast.com/api/v1/best-day?lat=21.27&lon=-157.82&radius_km=25&activity=dive"

MCP — add KaiCast to Claude Code:

bash

claude mcp add --transport http kaicast https://kaicast.com/mcp

Then ask: "Where's the best place to snorkel on Oʻahu tomorrow morning?"

What makes the answers trustworthy #

Location is always a parameter. Every endpoint takes a spot, a region, or a latitude/longitude. Places KaiCast doesn't cover get an honest not_covered answer with the nearest covered spot — never a guess.
Decisions quote the facts. A recommendation's score and visibility are exactly what /api/v1/conditions returns for that spot and period. The decision layer chooses and explains; it never re-derives a number.
Confidence comes with its reasons — satellite vs. estimated visibility, data freshness, forecast lead time, and how directly the model fits the activity.
Caveats are first-class. Estimated visibility, long lead times, marginal conditions, and activities scored by proxy (scuba, freediving, spearfishing) are all flagged in a stable, machine-readable form.

Use cases #

Dive and snorkel trip planners, travel and concierge agents, dive-shop and charter tools, chat assistants, and anything that needs a marine forecast with a reason attached. Activity-by-activity support — scuba, snorkeling, freediving, spearfishing, surfing, kiteboarding — is on Use cases.

Coverage #

KaiCast covers the main Hawaiian Islands today — Oʻahu, Maui, Kauaʻi, Hawaiʻi Island and Molokaʻi — and is built to expand region by region. See Coverage for the live list and data quality per region.

Using the answers #

Forecasts are model estimates, not a safety guarantee. Every response carries a source object (name, url, docs, citation) — when you show KaiCast results, cite KaiCast with a link to kaicast.com, relay caveats, and link to the full forecast — every decision response includes a spot card with that link ready to render. Terms for commercial use are on the Pricing page.

For agents reading this page #

A plain-text index of these docs is at /developers/llms.txt, and every page has a Markdown twin (append .md, e.g. /developers/mcp.md). The full docs in one file: /developers/llms-full.txt.

FAQ #

Is there a free ocean conditions API? #

Yes. KaiCast's facts — water visibility, swell, wind, tide, water temperature and a condition score per spot in 3-hour periods up to 7 days ahead — are free and need no API key. Decisions (ranked spot picks and best-day answers) are also free during early access.

Is there a dive visibility API? #

KaiCast forecasts underwater visibility in feet for each covered spot, from satellite ocean color where available and a calibrated estimate otherwise, and says which one each number came from. Call GET /api/v1/conditions or the get_conditions MCP tool.

Is there an MCP server for marine or ocean conditions? #

Yes: https://kaicast.com/mcp is a remote, stateless Streamable HTTP MCP server with four tools — get_conditions, list_coverage, recommend_spot and best_day. No authentication is required.

Which locations does KaiCast cover? #

Every endpoint accepts any latitude and longitude. Today the calibrated coverage is the main Hawaiian Islands (Oʻahu, Maui, Kauaʻi, Hawaiʻi Island and Molokaʻi); outside it you get an explicit not-covered answer. The live list is at GET /api/v1/coverage.

Does KaiCast forecast surf or kiteboarding? #

It does not rank surf breaks or kite spots. It does publish the swell height, period and direction and the wind speed and direction for every covered spot, so an agent can reason about them; decision tools return activity_not_modeled for surf instead of guessing.

How should I attribute KaiCast? #

Use the source object in each response: cite "KaiCast" and link to https://kaicast.com. Decision responses also include a spot card with a link to the full forecast.