Ben Chun - Round-Trip Angel Island

Counter-clockwise loop around Angel Island from Aquatic Park

16.1 km (10.0 miles)

5 hours, 37 minutes on 23 August 2023

Observed and documented by Kathleen Sheridan



  • Name: Ben Chun
  • Gender: male
  • Age on swim date: 45
  • Nationality: United States
  • Resides: Berkeley, California

Support Personnel

  • Terry Horn - kayak
  • Nathaniel Berger - RIB pilot
  • Lauren Au Brinkmeyer - photographer / spiritual advisor

Escort Vessel: Moon (AB Navigo 12VS) - Dolphin Club RIB


Kathleen Sheridan - Dolphin Club swim commissioner (2019-2022)

Swim Parameters

  • Category: Solo, nonstop, unassisted.
  • Rules: MSF Rules of Marathon Swimming, without exception or modification.
  • Equipment used: Textile swimsuit (Speedo Powerflex Eco) silicone cap, googles, earplugs, LED light.

Route Definition

Start @ Aquatic Park (beach between Dolphin Club and SERC), exit through Aquatic Park opening, counter-clockwise around Angel Island, return to Aquatic Park beach via opening.

  • Body of Water: San Francisco Bay
  • Route Type: island loop
  • Start & Finish Location: Beach between SERC & Dolphin Club docks, Aquatic Park, San Francisco (37.808145, -122.421402)
  • Minimum Route Distance: 16.1 km (10.0 miles) (map)


LongSwimsDB: Round-Trip Angel Island swims

Swim Data

  • Start: 23 August 2023, 06:01:23 (Pacific Daylight, America/Los_Angeles (UTC-7)).
  • Finish: 23 August 2023, 11:39:10
  • Elapsed: 5 hours, 37 minutes, 47 seconds.

Summary of Conditions

Feature Min Max
Water Temp (F) 64 66
Air Temp (F) 60 72
Wind (knots) 0 5

GPS Track

Trackpoint frequency: 10 minutes. Download raw data (CSV).

Speed Plot

Nutrition: Hammer Perpetuem (chocolate flavor) 8oz per feed. First feed at 45 minutes, then every 30 minutes.

Observer Log

Swimmer Statement

by Ben Chun

What inspired you to do this swim?

Lauren Au Brinkmeyer got me into swimming in the bay during the pandemic and took me to the Dolphin Club when it reopened. She’s the first person I knew who did Round-Trip Angel Island (RTAI), among her other impressive marathon swimming achievements. Before 2020 I was just a pool swimmer. That first summer I did a lot of swimming from Aquatic Park and even a round-trip Alcatraz. Learning the landmarks of the SF shoreline was fun, but the marathon stuff seemed a world away. I got cold easily. I started reading more about long swims and Angel Island kept coming up. It’s very big there in the Bay, and unless it’s foggy you can see that island from all over. You see it from all three bridges. You see it from the hills. And you definitely see it from Aquatic Park, looming like a supersized Alcatraz.

I did some open water races last year (Donner Lake, Waikiki Roughwater) and felt strong. I was ready for more. I decided to put all the Dolphin Club swims on my calendar this year and to swim through the winter for the first time. It was a cold winter and I got acclimated. At some point I started telling people around the club that I thought RTAI looked interesting. When Terry Horn said he would kayak for me, I knew I should take the opportunity. Terry kayaked for Lauren’s RTAI and for Cat Breed’s record-setting RTAI last year. When Nathaniel Berger said he would pilot the motorized boat for me, I knew I was going to do it.

Describe how you planned for the swim.

I have been helping pilot at the Dolphin Club for the past year or so, and a lot of what I know about planning a Bay swim comes from conversations with the DC pilots. They showed me how they think through the factors in a cross-channel swim, how to get current prediction maps for the bay, how to look at the bar pilot report, and how to talk to VTS. Terry picked the actual date, looking in the tide book for a neap tide.

For training, I laid out a calendar from mid-May to August 23 that more or less increased my yardage every week. My baseline was around 15k yards/week split evenly between pool and bay. I did a few more open water races this year (Lake Berryessa, Trans-Tahoe relay, Santa Cruz Roughwater) but the longest of those was 2 miles so not really pushing on endurance. I went to “swim camp” with some friends at a very cold lake in the foothills, where Conny Bleul swam with me and helped me figure out feeding. She is another inspiring athlete whose support really helped me prepare for this swim.

In June, I stopped wearing my thermal cap in the bay. In July I did some longer training swims, including a round trip to the Golden Gate Bridge (2.5 hours) and a round trip to Sausalito (4 hours), both from Aquatic Park and supported by Dolphins. This pushed my weekly yardage up to around 30k in some weeks and let me practice being in the water for a longer time and also practice feeding. The Sausalito swim gave me a lot of confidence that I was ready for this one.

How did the swim go, generally? Did you face any unanticipated challenges?

When I got to the Dolphin Club at 5:30 the crew was already there and the boats were on the dock. I was nervous but happy to see everyone. I gave Terry my feed bottles and went up the locker room to put on my suit and lube up friction spots. I’d given myself an abrasion during the Saualito swim from stubble on my chin and did not want to repeat that, so I made sure to shave my face the night before.

On the beach I realized my mirrored googles were very dark given the minimal pre-dawn light. But I knew I was going to want them later when the sun came up. The boats were already in the water. Terry said we were going out through Creakers and I didn’t know why, but I figured I could do that without being able to really see. I knew it was time to go. We did a countdown from 10 and I walked into the water. It felt cool but not cold and I felt good about that.

When Terry held up his paddle to signal my first feed (scheduled for 45 minutes) I had no idea where we were. I had not seen Alcatraz at any point in the swim so far, but was hoping to be on a pace that would put me North of the island by that time. Somehow between adjusting to the darkness of the dark goggles while the sun was coming up, it didn’t really register to me that we were in fog. But then I heard that there was a tanker coming through. I put my goggles on my head and saw that we were within a few hundred yards of Alcatraz and realized how low the visibility had become. No one wanted to be in the channel.

I could barely see the outline of the Alcatraz landmass and the lights on the dock and buildings even though it was right there. I told the crew I wasn’t cold and that I didn’t mind waiting. It felt like they were nervous. I swam toward Alcatraz a little just to keep moving, and eventually we could see the tanker coming. The fog had cleared a bit and I suggested that I could swim straight at it, knowing that it would be gone before we even got close. They agreed that I could do that. Back to the swim, and I tried to just put my head down and not worry about trying to guess how long we had paused, but it was in my head. I started alternating my breathing (like 3-2-3-2) which is not normal for me but the water was so calm I wasn’t getting waves on either side.

The next feed came quickly, and I could finally see Angel Island. Pulling up for the feed after that I felt upset that we still were not at Angel Island. But then I looked around and saw that we were actually right next to the rocks of Point Blunt. I had the experience multiple times during this swim of being disoriented about where I actually was and how much progress I was making. I felt like I had to pee but couldn’t.

Kept swimming and felt like I wasn’t moving along the shoreline as fast as I wanted to, so I started pushing harder on my kick and tempo. It seemed like there was a current running against me, and Terry moved us closer to the shore instead of taking a straight line. I knew that there would be some point where I would get into Raccoon Straight and should expect the rising ebb to help me, but I thought we were late and I was fighting it to get there. It seemed to take forever. Finally I could see Tiburon and after a little more fighting we did get into Raccoon Straight. I noticed how warm the water felt and I relaxed a lot, did some backstroke to try to stretch out, and enjoyed seeing the land go by faster. After a feed in the straight I was able to pee and that also helped.

Then the Golden Gate bridge came into view and I joked to Terry that all I had left was the hard part. This did turn out to be true, both physically and mentally. Terry kept angling us along the shoreline and I wanted to go straight toward Alcatraz. In another instance of me not knowing where we really were, I thought he was taking us much further East than we actually went. When we finally turned toward Alcatraz I was happy.

Then it was the long trip back. I knew the distance from Point Steward to AP was longer than AP to Blunt. I could see Alcatraz the entire time but couldn’t understand if we were on a good line or how much progress I was making. I knew I needed to just swim and so I tried to minimize my looking around, but I did keep checking on Alcatraz and felt unhappy about how much it did not seem to be getting closer. The conditions were beautiful and the water was very flat, so I tried to enjoy that. I could feel fatigue setting in and I was glad not to be in rough seas. At each feed I would do a little breaststroke to give my hip flexors a stretch. Eventually I could see Fort Mason. It felt like I could see Fort Mason for a long time before I could see the opening.

Finally I was back in the cove. Sprinting for the beach was not an option but I did try to pick it up, and soon enough I was between the docks and back on dry sand. I’d been doing a bunch of math in my head based on counting feeds and thought I was over 6 hours, which was disappointing. So when I found I had counted wrong and it was not yet 11:40am, meaning under 5:40 total, I was surprised and happy.

The lesson I am taking away from this swim is that I would be happier if I was thinking less, especially about time and distance. To attempt longer and harder swims I will need mental discipline, which didn’t really come up for me in training. Overall I feel lucky to have had such nice conditions and so much support for my first marathon swim.