About San Carlos Falls
San Carlos Falls was a moderately-sized 40ft plunging waterfall spilling into a very inviting plunge pool that was quite clear and full of fish.
In fact, this was said to be my guide’s favorite waterfall hike on Guam, and we even encountered a large group of military personnel who used their off-day to enjoy a swim here as well.
That said, the military folks that we met have told me that this place is typically not this busy, especially since it was a pre-Thanksgiving Day holiday for them.
Speaking of swimming, an excursion to the San Carlos Falls also can be extended to include an attractive cascade and plunge pool, which was informally referred to as the San Carlos Swimming Hole.
Curiously enough, the San Carlos Swimming Hole is on the Lonfit River, but the San Carlos Falls is on a seasonal tributary feeding the river, which also contains the Batan Falls (or Bijou Bataan Falls).
Unlike some of the other waterfalls that I’ve witnessed in my short time visiting Guam, I noticed that the farther away from “civilization” you are, the more clear the water.
In the case of these waterfalls and swimming holes, we did have to go on a somewhat moderate to difficult hike from Nimitz Hill in the southern center of the island, which took us a fairly leisurely 4 hours to go about 4 miles or so.
Of course, I should caveat that time duration because this included a few rest breaks, a lunch break, and some time to swim in front of San Carlos Falls.
On the day of our visit (the day before Thanksgiving in November 2022), we experienced both the San Carlos Falls and the San Carlos Swim Hole in a bit of a lollipop-shaped loop route, which is how I’ll delve into the rest of this write-up.
Trail Description – Hiking Towards The Lonfit River
From the trailhead parking near Nimitz Hill (see directions below), we essentially followed a series of roads (both paved and muddy 4wd tracks).
It began by following Turner Road until the first 4wd turnoff on the left, where we then took a brief interlude towards a different 4wd track that followed some power lines.
Next, we followed this power line flanked 4wd track for around 600-700ft to the next 4wd track on the right.
In my experience, this was the muddiest of the 4wd tracks, but it was only in the northern part of its 1/4-mile stretch.
Then, we went left onto a paved road that my map calls the US Naval Station Nimitz Hill, which had a trench being dug out alongside the road during our visit.
We continued east for another 1/4-mile before reaching a makeshift bridge going over the trench to our right (so there’s no guarantee this bridge will be there once this work is done).
From there, we followed yet another road for the next 1/4-mile, which meandered towards larger power pylons until ultimately terminating at the base of one such pylon.
Right behind this pylon, the track then finally became grassy and more naturesque as we undulated on some ridges flanked by swordgrass while also offering some views both to the east and to the west.
Towards the east, we saw the start of a watershed system before dropping off in a pair of gullies, which my guide said that the Batan Falls was.
The waterfall itself wasn’t that visible during our visit due to the thickness of the vegetation combined with lower waterflow.
Meanwhile, looking in the opposite direction to the west, we noticed the radio towers sitting atop Mt Alutom, which was where I had hiked to both Upper Sigua Falls and Maguagua Falls.
Continuing in a southeasterly direction, the track eventually dropped towards a grove of palm trees where we then followed a fork in the faint trail to our right.
This fork ultimately marked the beginning and end of a looping route that would encompass both the San Carlos Falls and the San Carlos Swimming Hole.
According to my GPS logs, it took roughly 1.5 miles from the trailhead to reach this decision point.
Trail Description – The Loop Encompassing San Carlos Falls and San Carlos Swim Hole
Our group ultimately opted to do the looping part of this trek in a counterclockwise direction (though the military guys we met ended up doing this loop in a clockwise manner).
So this trail description is happening in this counterclockwise direction, which is contrary to the suggested route described in “The Best Tracks on Guam” book (advocating for an out-and-back route).
Regardless, it didn’t take long on the fork that we took as we went through some swordgrass before the path descended steeply down a muddy (i.e. very slippery) slope with some rope tied to some trees for leverage.
This rope-aided muddy slope was one of the reasons why this hike is considered “difficult”, and like other undeveloped hikes in Guam, you’ll definitely want to be wearing long-sleeved shirts, long pants, and gloves.
After carefully making our way down to the bottom of this decline, we then found ourselves on the banks of the Lonfit River right above the small waterfall spilling into the San Carlos Swimming Hole.
The river here was notable because there were lots of tadpole-looking “dots” in the calmer parts of the river.
Anyways, the river was also shallow enough to be able to cross the stream without getting Gore-tex boots wet, and we then carefully used rope to descend alongside the far western side of the falls.
Once at the bottom, we then scrambled towards the front of the plunge pool, where we then started a riverbank scramble along the Lonfit River downstream for the next 700ft.
Eventually, our scrambling along the north side of the Lonfit River brought up to a confluence with a tributary stream, where we then followed the west side of its banks upstream for the final 700ft or so.
Along this stretch, there a bit more stream walking or at least walking on very slippery rocky stream beds, which was another part of this hike that made it more difficult.
At least we approached the San Carlos Falls and its inviting plunge pool without much elevation change, and it was perhaps the most suitable way to approach the falls.
When we arrived, we saw a large group of military folks on their off day either already in the plunge pool or still climbing down a steep slope alongside the east side of the falls itself.
As for the plunge pool fronting San Carlos Falls, I noticed that the water was very clear, but I also noticed that there was a pretty large group of fish as well.
Anyways, that slope with the rope turned out to be the route that we would take on the way out.
Therefore, it probably didn’t matter which way we went (either clockwise or counterclockwise like we did) as far as difficulty was concerned.
However, I did appreciate the counterclockwise approach that we took because of our approach to the San Carlos Falls itself.
So after having our fill of the San Carlos Falls, we then climbed up the rope-assisted incline eventually going higher than the tributary stream before dropping back down to it right at the brink of the San Carlos Falls itself.
From there, we continued stream scrambling (on slippery bedrock surfaces) for about 400ft or so before reaching a steep incline that also involved the use of rope to get out of the tributary’s drainage.
Our guide mentioned to me that had we continued stream scrambling further upstream, we’d eventually reach the Batan Falls.
Anyways, after about 200-300ft or so, we’d eventually return to the grassy slope, where we then went back the way we came along a series that ridges and roads that we had taken on the way in.
Although this hike was pretty much a fairly difficult 1/2-day excursion, I had to say that it probably felt the most rewarding when you consider the pain versus pleasure equation, especially compared to say Tak’hilo Falls.
San Carlos Falls resides near Nimitz Hill in the village of Yona and Asan, Guam. It may be administered by the Guam Department of Agriculture. For information or inquiries about the area as well as current conditions, you can try visiting this website.
The trailhead for San Carlos Falls sits a short distance to the west (or southwest) of Nimitz Hill near the intersection of Larson Road and Turner Road (both by the Route 6).
Even though the trailhead parking was not officially signed, there seemed to be a few large clearings flanking Turner Road making it seem like a pretty obvious spot to start a hike (though not necessarily obvious to start the San Carlos Falls hike).
To get here from Tumon Bay, we’d drive west on Marine Corps. Drive (Hwy 1) for a little over 8km to its junction with Route 6.
Turning left onto Route 6, we then drove about 5km towards Larson Road (not far past Nimitz Hill) before turning left onto that road.
Then, at the T-intersection between Larson Road and Turner Road was the parking for the San Carlos Falls hike.
Overall, this drive took us under 30 minutes.
Finally, for geographical context, Yona was about 18km (under 30 minutes drive) north of Inarajan, about 19km (under 30 minutes drive) south of Tamuning, and 20km (about 30 minutes drive) south of Tumon Bay.
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