San Juans Cellular Map for Boaters

Over the last year I’ve started recording cellular signal strength and download speeds in the anchorages we’re in. While previously we were happy to have some time away from the Internet, recently it’s become more important to stay connected. This is our third year of semi-full-time cruising with no home port, and with the Canadian border closure this year we can’t go very far. So we’ve spent more time online for video calls with friends/family, work, and entertainment.

It’s often helpful to know whether we’ll have fast Internet in an anchorage before we go there. You can look at the cellular provider’s own coverage map (T-Mobile, AT&T). However these maps aren’t very accurate for boaters, and say they have 4G coverage in places where they definitely don’t. They’re not customized to the particulars of a boat in an anchorage. Getting actual, real-world speed measurements is much more reflective of how fast and reliable the signal is in a given anchorage.

The way these cellular speed measurements were collected was through the app on my Pixel 3a phone, usually from the cockpit of our boat. Our Internet service is a Google Fi unlimited plan, which uses a combination of cellular networks (T-Mobile, Sprint and US Cellular, in the US) and includes roaming in Canada (or other countries) with no increased data charge. I have heard T-Mobile is better than AT&T in the San Juans, so the results below are most relevant for T-Mobile/Sprint (which have merged).

A few caveats apply to cellular speed measurements: the results may vary based on many factors, including the weather, position of your phone, what kind of phone or service you have, and location of your boat in the anchorage (if you’re next to a big cliff that blocks the cell tower, you could have very different results from someone on just the other side of the anchorage).

This is just a screenshot. See below to get the interactive map.

You also may get better results if you have Internet enhancement onboard – such as external antennas or a booster. However these base Speedtest results are still useful for making relative comparisons – for example, we know that we can get very fast speeds in West Sound or Blind Bay (60 Mbps) but slow speeds in Lopez Sound in Hunter Bay or Mud Bay (3-5 Mbps). And on just the other side of Lopez, in Fisherman’s Bay we get the fastest speeds we’ve found in the San Juans (127 Mbps down, 25 Mpbs up).

I’ve mapped locations not just in the San Juans but also in Puget Sound and the Bellingham/Anacortes area. But I titled this post San Juans cellular map because the majority of locations are from there since it’s our home waters currently. Also, these are the anchorages where knowing the cellular strength is more important – finding a strong connection in central Puget Sound near major populated areas (Seattle, Everett, Bainbridge, etc) is usually not a problem. The San Juans are where we find some areas, such as Sucia Island, that can have little to no signal in some places.

San Juans Cellular Map:

To see it full screen in a new tab, click the full-screen icon in the upper right. 

  • Color code for icons on the map:
    • Green = fast
    • Orange = okay (5-10 Mbps down)
    • Brown = Slow (< 3 Mbps down or < 0.5 up).
    • As a rough guideline, fast means you can do streaming video (Zoom calls, YouTube, etc), orange means you can do video but probably at lower quality, and slow means you can probably do email and webpages but downloads or video will be really slow or not possible.
  • To see it full screen in a new tab, click the full-screen icon in the upper right.
  • Scroll south to see measurements in the Port Townsend area. I don’t have recordings for any areas further south at this time.

If you appreciated this map and are planning to signup for Google Fi on a compatible device, please use my referral link so we’ll both get a $20 credit. I’ll try to update this map over time as we visit anchorages it doesn’t cover yet (not many in the San Juans), so feel free to bookmark this page and refer back to it.

Recently we also added an LTE hotspot with external antenna options (the Netgear Nighthawk M1 LTE Router) so if you’re dependent on fast Internet you may want to check out this post: Adding Cellular Internet Enhancement to Our Boat (Something We Never Expected to Do!).

2 thoughts on “San Juans Cellular Map for Boaters

  1. Kathy Halstead

    This is such useful information for us. Thank you! We use Google Fi as well. Last year we were happy to have service at Rosario Resort. Friday Harbor, Roche Harbor, and La Conner all have good service this season.


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