Unidentified Vessel / Tour Boat (Imperial Beach — 220 fsw)


This is another case where we had seen some ROV footage of a large “yacht-like” vessel and had an approximate location but hadn’t been able to pinpoint it. After multiple attempts to locate it, I went with Lora and Chris on the Marissa for another attempt — but this time we had the sonar system on the Marissa. Tyler was working so it was just me on the boat.

Locating the wreck

We got down to the general location and started looking around again with the sonar to find anything that looked like a potential target. We knew that the vessel was somewhat large and we knew the location of the proverbial “haystack” — now we just needed to find the needle.

Tyler had looked there before but couldn’t find anything specific using the older sonar system Lora had. He also had a location from a study that Roy Pettus had conducted back in 1987. There was also a “blip” in the bathymetry data that Tyler had noted.

Now that Lora had the new sonar system on the Marissa, we decided to go back and look around that area and the different data points to see if we could find anything worth diving.

After a while, we found something that looked pretty good. You can see in the image below the different spots we had tried. I’m pretty sure that the image on the sonar is from my when I had started my ascent and I was venting gas from my rebreather and my drysuit.

Below is a side scan image of one of the waypoints:

The Dive

We had really nice visibility on the day of the dive (30 Oct 2021).

I got geared up, jumped in, got my camera and headed down the line. I remember that when I got to about 180 feet I could see white metridiums and immediately knew that we had found our target. Here is a picture I took on the way back up the line but it will give you a sense of what I saw when I first was headed down and will also give you a sense of the visibility on that day:

Unidentified vessel near Coronado Islands

Since I was alone, I didn’t venture inside the vessel although I believe that it is possible — likely through the sunroof on the front portion of the deck (more on that in the photos). I spent about 10 minutes taking photos and looking around on the initial dive and then had about 40 minutes of decompression and a total run-time just under one hour. Since the first dive was just to find the target, I didn’t bring my normal arsenal of tape measures, scrub brushes, etc.

Photos and Notes

It is a somewhat “confusing” to identify as it is not structured like most vessels. Here are some overall notes:

  • The helm area on top is obvious and our initial though was some kind of luxury yacht; however, there aren’t really any open deck areas so that somewhat rules it out.
  • It doesn’t appear to be a fishing vessel because there aren’t any open areas at the stern.
  • You can also see all of the open windows along the sides of the vessel which indicate viewing the outside from most locations
  • There isn’t any obvious way to get into the passenger area of the vessel (but more on that in the detailed photos)
  • It is a relatively narrow beam which means it might have been designed for speed.
  • I didn’t measure the wreck, but I would estimate it at 50-60 feet long
  • It appears to be mostly stripped and I didn’t see any anchor or line at the bow.

Below are some of the key photos I took.

After talking with Steve Lawson, we believe that this might have been a tour boat. Possibly designed to take passengers down for tours of the Coronado Islands. Tyler and I both did extensive research and could not find record of any boat sinking in that area. We believe that it was purposefully sank but do not know that for sure.

Stern Section

Below are photos of the port, central, and starboard sides of the stern. Note that the sand is very deep covering any props that might be left and/or potentially the name of the vessel. Also note that there is no room at the stern for fishing, sitting on deck chairs, etc.

Stern Section Windows

This is the view from the starboard stern corner going towards the bow. You can see all the large “picture” windows. The height, based upon where the deck level is inside, would indicate eye level. Again, maybe a clue that this vessel was used as a tour boat.


The helm is up on top of the vessel and you can see a stairwell going down into the main deck area on the right side. The steering wheel is in place still but all other controls have been removed. You can still see the wires and cables that were presumably attached to the controls. You can also see a plate with holes in it that presumably had the gauges attached.

Skylight / Interior Galley & Head

Just forward of the helm is a relatively large opening. I believe that a diver could wiggle through this hole. I’m guessing that it was a skylight to add some light into the galley and head that were below it. I stuck my camera inside and took a few pictures of the interior.

Bow Section

Pictures of the bow are below. Note that there are no lines, chains or anchor.

Port Side of the Helm

There are still some mysteries that need resolving. Obviously, the name or identification is the biggest one. I didn’t spend a lot of time on the wreck looking for any specific identification (this dive objective was to locate the wreck). The other mystery is how people got onto the boat and into the main cabin area. Steve Lawson reviewed the pictures I took and has a theory on the latter.

Two things to note specifically about the picture below:

  1. There is a blue stripe across the helm. Could the name of the boat or cruise line be on that? Also note that there appears to be a portion of a logo near the back of the blue stripe. Could this be a clue?
  2. Steve noticed a “disconnect” or a break in the hull structure in the photo below. It looks like there might be a hinge and then a panel that would drop down. Is this possibly a boarding plank? There is also a similar panel on the starboard side.

Next Steps

I’m not sure if/when Tyler and I will get back to the site. It is quite a long boat ride and we are currently working on other projects.

We have decided to publish the location of the wreck in case somebody else has the desire to do more research in order to identify it. Please remember that it is a relatively deep dive (220 fsw) and you need the training & experience to conduct any dives on the site. Also, if you do find more information, we would appreciate letting us know so we can update the post.

I’m not sure we had the exact position of the wreck, but the data points below are all within a very short distance and should allow anybody with a sonar to locate it exactly.

Lora’s Marissa Location : 32° 33.990 N , 117° 16.231 W

Pettus Study Location : 32° 34 00.37 N , 117° 16 08.41 W

ROV Location : 32° 33′ 59.41″N, 117° 16′ 13.97″W

3 thoughts on “Unidentified Vessel / Tour Boat (Imperial Beach — 220 fsw)

  1. Note that Pettus’ numbers were likely NAD27. If we convert them to NAD83 (very close if not identical to WGS84), we get N32 34.010 W117 16.192. This distance is much closer, some 237’ from the other two coordinates.

    I would think the boat was designed more for harbor cruises, where the water is calm. The open unprotected flybridge and large windows near the waterline would not be good for the open ocean. Given the absence of an anchor, railing, electronics on the bridge, cushions or anything else inside seems to suggest the boat was stripped and intentionally scuttled.


    1. Yes, I agree with you on all points. The real question is: why would they take it all the way down to where it is to sink it vs. putting in in “wreck alley” or someplace closer? That is a mystery.

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