Open water swimming in San Francisco Bay means cold water and strong tidal currents, in a harbor with ships and ferries moving all day. The safe way to cross it is with a swim pilot, a licensed captain running an escort boat beside you. Below are the routes Captain Molly escorts, the water temperature by month, the main risks and how to plan a swim.
What an escort boat does for a Bay swim
The escort boat navigates for you and acts as your safety boat. Your coach, feeds and warm clothes ride aboard.
- Traffic: the Bay is a working harbor. Captain Molly watches cargo ships, tankers and ferries on AIS and radar and keeps your swim clear of them.
- Tide and current: the start is planned from the current predictions so the current carries you toward the finish instead of away from it.
- Weather: Fog, wind and chop (worst when the wind runs against the tide), smoky air and ship traffic can each move or cancel a swim, and Captain Molly makes the call. In fog, other boats can’t see a swimmer.
- Logistics: gear, feeds, a coach, an official observer and family travel aboard, up to 6 people in total, and the heated cabin is there for thermal recovery afterward.
Swim pilot, escort boat, kayak: what each does
- Swim pilot: the licensed captain who runs the boat, reads the current, plans the line and the start time, and makes the go/no-go call. On Miss Molly that’s Captain Molly, who holds a U.S. Coast Guard Master license (100 GRT, Near Coastal) with a Radar Observer endorsement.
- Escort boat (also called a pilot boat, support boat or safety boat): the boat itself. It stays beside or behind the swimmer, never in front, so the swimmer can sight on it without it blocking their line, and it carries the crew, the feeds and a way out of the water.
- Kayak: a paddler who stays right beside the swimmer to hand feeds and keep eyes on them. On Molly’s swims a kayaker is available at extra cost; ask for the price.
- Observer: a person aboard who watches and records the swim for a sanctioning body. Official observers are welcome on every swim.
San Francisco Bay swim routes
Captain Molly escorts these routes. Each one is planned around the current on the day, so check jump times on /jumptime before you pick a date.
Alcatraz to the St. Francis Yacht Club
The best-known Bay swim. The boat takes you out to Alcatraz, you get ready aboard and jump in, and you swim back to the city, finishing at the St. Francis Yacht Club. It’s about 1.5 miles in a straight line and 1.7 to 1.9 miles as swum, because the current pushes you sideways, and it takes most swimmers about an hour. Without an escort boat holding your line, it is easy to be carried past the finish. $550 per boat. See the Alcatraz swim and check Alcatraz jump times.
The Bridge to Bridge 10k
About 6 miles along the waterfront between the Golden Gate Bridge and the Bay Bridge, marketed as a 10k. The usual direction is Golden Gate Bridge to the Bay Bridge on the flood, and Captain Molly plans the direction and start from the current. The time depends on the current and your pace, and the boat is booked for 3 hours. $700 per boat. See the Bridge to Bridge swim, check the current on /jumptime, or step up to marathon training blocks.
Around Angel Island
A swim around Angel Island, working across the sideways currents of the central Bay. It’s often quieter than the city-front swims, but holding a line takes careful piloting. The boat is booked for 3 hours, $1,080 per boat. See the Angel Island swim and check the current on /jumptime.
Marathon swim training
For swimmers preparing for a marathon swim, Captain Molly runs a pilot boat for 4 hours, 6 hours or 8 hours, at $350 an hour for the boat: $1,400, $2,100 or $2,800. You bring the plan, the feeds and your coach or observer. These are quoted: send Captain Molly your plan with the Ask Molly button, after checking the current on /jumptime.
Want a different route, such as a Golden Gate Bridge crossing? Ask Captain Molly with the Ask Molly button.
Is it safe to swim in San Francisco Bay?
The main risks for a Bay swimmer are the cold, the current and the traffic. Sharks are the question people ask most, so the figures are below too.
Cold water
The Bay is cold year-round. The National Weather Service warns that cold shock “can be just as severe and dangerous from water temperatures of 50–60°F as it is from water at 35°F,” with gasping in the first 2 to 3 minutes, and that hypothermia begins at a core temperature of 95°F. That’s why Captain Molly asks every swimmer whether they’ve swum open water in the Bay or only in a pool, and whether they’re experienced in cold water.
Sharks
Shark incidents are rare in California. The California Department of Fish and Wildlife counts fewer than 250 shark incidents along the whole state’s coast since 1950, fewer than 20 of them fatal. Its study of 1950 to 2021 found 201 incidents and 15 deaths, fewer than 3 incidents a year statewide.
Currents and traffic
Tidal currents in the Bay can carry a swimmer far off their line, and ships, tankers and ferries move through it all day. With an escort boat, the swim is timed to the current and the boat keeps you visible. If you need to get out, it can pull you from the water quickly.
Water temperature by month
Long-term monthly averages for NOAA’s San Francisco station (9414290). Any given day can run a few degrees either side.
| Month | Average water temperature | What to wear |
|---|---|---|
| January | 52.5°F | Coldest water of the year: your full cold-water setup |
| February | 53.2°F | Coldest water of the year: your full cold-water setup |
| March | 54.1°F | Your full cold-water setup |
| April | 54.7°F | Your full cold-water setup |
| May | 55.7°F | What you train in for cold water |
| June | 57.3°F | What you train in for cold water |
| July | 59.6°F | Warmer, still cold water: what you train in |
| August | 61.2°F | Warmest months, still cold water: what you train in |
| September | 61.5°F | Warmest months, still cold water: what you train in |
| October | 59.8°F | Warmer, still cold water: what you train in |
| November | 57.0°F | What you train in for cold water |
| December | 53.7°F | Your full cold-water setup |
On wetsuits, Captain Molly asks you to wear what you normally wear for a cold-water swim, broken in. Know your equipment before you jump, and don’t try a new suit, cap or goggles on swim day.
Frequently asked questions
How far is the swim from Alcatraz to the city?
From Alcatraz to the St. Francis Yacht Club, where Molly’s crossing finishes, it’s about 1.5 miles in a straight line and 1.7 to 1.9 miles as swum. How far you actually swim depends on the current and how well your escort boat helps you hold your line.
Do I really need a support boat for an Alcatraz swim?
Yes. The Bay is a busy shipping channel with strong currents. An escort boat keeps you visible to other vessels and gives you a quick way out of the water if you cramp or get too cold.
What happens if there’s fog on the morning of my swim?
Captain Molly makes the call that morning. If the fog is too thick to keep you and the shipping traffic in view, the swim waits or moves. If she cancels for weather, you get a full refund or a new date.
Can the boat carry my coach or family?
Yes. It’s a private charter: up to 6 aboard in any mix of swimmers, coach, observer, family or kayaker, and the price is per boat, not per swimmer.
How do I book?
Check the current on /jumptime, then book the Alcatraz, Bridge to Bridge or Angel Island swim online, paid in full at booking. Cancellation is free up to 7 days before. For marathon training or any question, use the Ask Molly button. Captain Molly replies in writing within 24 hours. More answers are on the FAQ page.
Plan your swim
Every swim leaves from Hyde Street Harbor at Fisherman’s Wharf aboard Miss Molly, a 27-foot Shamrock Mackinaw 270 with a heated cabin, a private bathroom, radar, AIS and an EPIRB. See all swim escort routes and prices.
