Los Penasquitos Lagoon

One of my favorite places to explore for over the past 30 years in the Los Penasquitos Lagoon. I would like to take you on tour, would you join me?

Ok! Let’s go!

Los Penasquitos Lagoon

Located between the city of Del Mar to the north and the border of San Diego to the south, the Los Penasquitos Lagoon is a 510-acre coastal salt marsh estuary.

Translated from Spanish, meaning “The Little Cliffs,” the Los Penasquitos Lagoon frames the northern part of the Torrey Pines State Natural Reserve and is designated as a Natural Preserve.

Los-Penasquitos Lagoon

 Los Penasquitos Lagoon is one of the last remaining salt marshes left in southern California. In other words, the lagoon supports a large variety of plants and animals, including seven threatened or endangered species.

Another interesting fact is that this lagoon also serves as a refuge for migratory birds that use the Pacific Flyway.

Since joining the State Park System, there have been quite a few changes to help increase the overall tidal flow here at the Los Penasquitos Lagoon.

Let’s now have a look.

12600 N Torrey Pines Rd, La Jolla, CA 92037

Parking Fees

Places nearby-   Torrey Pines State Beach

Torrey Pines State Natural Reserve

Activities- Hiking, bird watching

Los Penasquitos Lagoon History

 Development within the lagoon in the 1880’s and the 1930’s have modified the lagoons hydrology process.

There are several reasons for how this eventually happened.

Los Penasquitos Lagoon train tracks
Train Tracks

Sante Fe Railroad Track

First off, in 1925 the Sante Fe Railroad built a single-track roadbed causeway embarkment down the center of the lagoon for its Surfline.

Can you believe that this track is still in use today on a daily basis?

Train Tracks over Los Penasquitos Lagoon
Credit-Wikimedia Commons

The embarkment severely restricted the normal historical lagoon drainage for the first time and ultimately this changed the tidal flow.

Highway 101 Bridge

Los Penasquitos Lagoon man in front
Do you notice all the pilings on the original bridge?  (circa 1993)

In the 1930’s the Pacific Coast Highway, otherwise known as US Route 101 was expanded, the roadbed along the beach heightened, and a bridge built over the mouth of the lagoon.

The waterway under the bridge would continually get clogged with sand and debris due to the 72  wooden pilings.  This debris, in turn, would impact the flow of water between the ocean and the lagoon.

In 2005, a new bridge was built for uninhibited water flow.

Do you notice that there are only four cement pilings?  Because of this, the lagoon being closed off by sand and debris doesn’t happen anymore.

Los Penasquitos Lagoon Bridge

Los Penasquitos Lagoon inlet under bridge

Los Penasquitos Lagoon inlet ocean
Uninhibited water flow is a beautiful thing!

Los Penasquitos Lagoon inlet Torrey Pines State Beach

Due to the very low tide, the tidal flow out to the beach is stronger than usual.

Fun fact- My husband and I would consistently come out here to Torrey Pines State Beach back in the early 1990’s when we were dating.

One of our favorite things to do was to go at night with flashlights. We would shine the light into the mouth of lagoon looking for Gray Smoothhound sharks and other fish. Their eyes would glow green with the reflection of light.

Gray Smoothhound Los Penasquitos Lagoon
Gray Smoothhound
Credit- Nathan Rupert

Let’s now have a look at the mouth of the lagoon from on top of the bridge on Highway 101.

North Torrey Pines Beach
Looking toward North Torrey Pines State Beach

Los Penasquitos Lagoon inlet Torrey Pines State Beach
Notice all the sediment leaving the lagoon?

Do you see the metal pole sticking out of the water towards the left? That is a monitor that keeps track of the tidal flow that comes in and out of the lagoon.

North Beach Entrance Parking Lot

Los Penasquitos Lagoon North Parking Lot
Credit -Wikimedia Commons

In 1983 the Los Penasquitos Lagoon Foundation was established. The primary function of this foundation, to this day,  is to keep the mouth of the lagoon open, improve circulation of the lagoon as well as to restore habitat.

According to the Los Penasquitos Lagoon Foundation and the State Coastal Conservancy, the building of the fully paved North Parking Lot in 1968, considerably altered the lagoons hydrology (water circulation).

Could this lagoon ever catch a break? First, off the railroad, then clogged bridge pilings and then finally a cement parking lot. All three structures played havoc on the water circulation!

North Parking Lot Los Penasquitos Lagoon
North Parking Lot
Los Penasquitos Lagoon
HWY 101  view.
North Parking lot view lagoon
North Parking lot view.
Birds Los Penasquitos Lagoon
There sure are a lot of birds here!

Continuing from the North Parking lot and following Carmel Valley Road, there is an unofficial path in which you may view the lagoon from behind a barrier. Let’s go!

East view Los Penasquitos Lagoon

Los Penasquitos Lagoon trees background hill plants

Los Penasquitos Lagoon California Buckwheat Front

Los Penasquitos Lagoon East view

Los Penasquitos Lagoon Trails

Los Penasquitos Marsh National Preserve Boundary Sign

Although almost all of the lagoon is off limits to the public, there is one trail- The Marsh Trail that is open to exploring!

To reach this trail, you must start at the South Beach entrance off of North Torrey Pines Road (HWY 101).

South Beach Entrance Los Penasquitos Lagoon
South Beach Entrance- South Parking Lot

You will find the trailhead not that far south on the east side of the road. The trail winds around the western side of the Reserve, finally ending up in the industrial area of Sorrento Valley.

Marsh Trail Los Penasquitos Lagoon
Beginning of the Marsh Trail. Do you notice the North Parking lot in the background?

This trail is not a loop, so you must turn around and come back, so keep that in mind. If you go to the very end, the roundtrip would be about 4 miles.

There are many plants and animals to look out for, so keep your eyes open!

My Special Place

Los Penasquitos Lagoon 1993
Los Penasquitos Lagoon -Circa 1993

Well, thank you so much for joining me on a tour of the Los Penasquitos Lagoon. As you can see, it is not enormous, but it sure has character.

Check back later as I plan on taking a hike on the Marsh Trail in the near future!

As I have previously stated, this lagoon has always held a special place in our hearts. I feel incredibly fortunate to have seen so many improvements and witness the transformation this lagoon over the last 30 years.

Under Bridge Los Penasquitos Lagoon

The new bridge has a lot to do with this, so thanks to the new bridge! Thank you for allowing more water into the lagoon and improving the circulation.

And a special thanks goes to the Los Penasquitos Lagoon Foundation for all the hard work and dedication they all put into preserving as well as researching this environment.

 I hope that one day you may witness the Los Penasquitos Lagoon in person. There are so many beautiful places to discover in San Diego, especially the beaches of San Diego!

Please leave any comments or questions that you may have down below.

Until next time!

Learn How To Make A Business Website For Free!

Los Penasquitos Lagoon


I have always had a deep-seated passion for the Ocean Environment which ultimately led me to receive a degree in Marine Biology. Living in the San Diego area for over 30 years, I have extensively explored the 70 miles of San Diego’s coastline, and I am here to share! Please use my website to your advantage and have a look around at all the wonders that the beaches of San Diego can offer you!

2 Replies to “Los Penasquitos Lagoon”

  1. It looks like a nice place to go for a walk and take in a little bit of scenery. I do like to watch birds from time to time. Are there any bird huts located there to spy on them in the marsh?

    1. Thank you for visiting Owain. I am not sure if there are any bird huts on the Reserve, especially at the Lagoon. I have read that on the Marsh Trail there are some big trees, so I suppose that would help with some cover to watch the birds in the marshland. I will have to get back to you after I try the trail out! Thanks again for your question. I do have a suggestion on where you can go that does have some natural barriers to observe bird up close. https://70milesofcoast.com/a-walk-around-buena-vista-lagoon

Leave a Reply

Your email address will not be published. Required fields are marked *