In-Depth Discussion with Ocean-Navi: Tsugaru Strait Channel Research (Part 2)

At this stage, WOWSA’s role is purely investigative. There are some public calls on social media to replace the Tsugaru Strait in the Oceans Seven or offer additional channel swims for swimmers to choose their preferred O7, but our goal at the moment is to present the information gathered in order to have a more informed dialogue both with the WOWSA Advisory Board and the broader marathon swimming community to determine the best course of action, if any. 

As part of the investigation, we contacted Shimasaki Yusuke by phone, a Japanese travel agent who serves as the liaison and translator between Ocean-Navi and international swimmers who wish to attempt the Tsugaru Strait. Yusuke was not comfortable speaking on behalf of Ocean-Navi and did not provide details on the origin or timing of the rule change prohibiting swimming at night. He did say that the new rule was the result of “discussions between the Japanese Coast Guard and a regional association of Japanese fisherman.”

We reached the President and Founder of Ocean-Navi, Masayuki Moriya by email, translated through Mika Tokairin, who serves as an observer for Ocean-Navi.

You can also read Dean Summers’ report on his experience attempting the Tsugaru Strait. And are including a spreadsheet comparison of Ocean-Navi, TSSA (Tsugaru Strait Swimming Association) and independent crossings.


  • There is no law specifically stating that swimming before 3 am is prohibited.
  • Ocean-Navi is blaming low success rate on climate change.
  • There is a 14-hour time limit for the swim.
  • Captain will charge extra after 10 hours
  • Special permission to swim before 3 am is not granted. There is no exception or possibility to bypass the rule and swim at night.
  • Ocean-Navi made these rules in consultation with the captain and enforces them.
  • The new rule prohibiting swims at night and enforcing a 14 hour cutoff are communicated online in Japanese, but are missing in the English version and only communicated days in advance.
  • Information on the Ocean-Navi website is outdated, including linking to WOWSA on Japanese version and mentioning Open Water Source in the English version.

Ocean-Navi Response Email #1:

  1. To your question about night swim:

We have been avoiding night swims in accordance with the request from the Japan Coast Guard that “if visibility cannot be maintained for more than 1 km, we ask that you refrain from conducting night swims.” The Tsugaru Strait is an international strait, and large vessels, including Chinese and Russian warships, frequently come and go. Also, due to the ocean currents, trash and large pieces of wood generated from the recent frequent floods also arrive here. Incidentally, there are currently many floating debris from the flooding in Akita Prefecture that occurred a few days ago. Due to these circumstances and reasons, we do not conduct night swims.

  1. To your question about the reason why the success rate is so low

As for the success rate, last year it was 50%. This year, no one has reached so far. It is true that the success rate is very low. But that is not our intention. The possible reason is that the strength of the currents, the time of their occurrence, and the area of occurrence are no longer readable, possibly due to climate change. It appears that unprecedented current conditions are occurring. Under these conditions, we look at the wind and wave conditions at the time of the start, as well as the forecast for that whole day, to determine whether or not to start. So far this year, there have been a variety of reasons why we have not been able to reach the other shore, and it is by no means just the current.

Tulasi Chaitanya, for example, suffered from wave sickness and even vomited, despite favorable conditions with almost no waves and no currents, and decided to quit by himself.

Rob Lea decided to quit by himself. When the current began to get stronger, we talked to him that he had a choice to continue but the current is going to be stronger with 90 degree angle, then considering the shoulder pain he was suffering for a while, he chose to quit.

In Dean Summers’s case, there’s no current at his start, just wind and waves, but about 1 hour later we had an unusually early current and got swept out to the area with stronger current, and we considered the conditions in the waters beyond of that area which currents get even stronger, we asked him to stop, and he agreed.

In Sarah Thomas’ case, the weather conditions did not allow to start within her given window. On the last chance day, although we told her that she could not start due to strong winds and waves, she strongly insisted that they were fine and that they should be allowed to swim, but we could not allow her to start with the safety of not only the swimmers but also the crew and staff of the escort boats in jeopardy.

These are the facts of what is happening this year. If you have any questions, please contact us again.

Email #2

Could you please answer only yes or no to the following questions.

1. You say “if visibility cannot be maintained for more than 1 km, we ask that you refrain from conducting night swims.” Is there a law that specifically states, you can not swim before 3 am? Yes or No?


2. Your website does not mention a 14 hour time limit. It just says 10 hours is a guideline. Is there a 14 hour time limit? Yes or No?


3. Is Steven Munatones still part of your organization? Yes or No?


4. Is there a ratifying body TCSA? Yes or No?


5. Do you charge extra after a certain hour? Yes or No?

After 10 hours, the captain charges extra per hour up to 14 hours. (we don’t)

6. Is there a way to get permission to swim before 3 am in special cases because previous swims had permission? Yes or No?


7. Who is doing the records for you?

Ocean Navi, with the report from the observers

8. Is Steven processing the records?


Email #3

1. Since when did the 14-hour time limit, not allowing vessels to leave port before 3:00 a.m. and return before sunset, apply?

Since 2022, we set the 14 hour time limit. 

2. Who makes these rules (Coast Guard, fishermen’s union) and who enforces them?

We made it, taking into account the Coast Guard’s request and after consulting with the captain, and we and the captain have the authority to enforce it. 

3. Are these rules published in any official rules or regulations? If so, where is it listed and what is the exact wording?

The 14 hour rule has been in place since 2022, and it’s written in the Japanese information we send out to swimmers before they sign up. but it was missed out in the English document for international swimmers. When we received complaints about it when the first swimmer swam this year, and became aware of it, and hastily let other swimmers know this rule. We believe this is a major reason for other swimmers disbelief. We sincerely apologize for it.

4. Is there any exception or possibility to bypass this rule and swim at night?

We are afraid that it is difficult under the current circumstances. 

5. Is there anything you can say to the community to convince them that they should still plan a Tsugaru attempt after the failed 11/11 solo attempts this season? Why?

As we wrote in the earlier email, this year’s situation was not predictable in advance. The same is true for future situations. Whether it is worth the cost is not for us to say. It is for you to decide. 

6. What is Ocean-Navi’s official refund policy and procedure?

25% for not starting, 0% if started.

Thank you. We always work hard for the success of the swim, and also the safety for everyone involved

Thank you for your understanding.


Mika Tokairin of behalf of Masayuki Moriya

Email #4

Dear WOWSA and Mr. Fitzgerald,

Again thank you for your patience. We reply to these two remaining questions from you.

Why is Steven Munatones on your website? Why do you mention you work with Open Water Source which is a site that does not exist?

When we started to support international swimmers in Tsugaru Straight, Steven gave us a lot of advices and he still does to us time to time. We pay him some honorarium for his knowledge and insight, but we are separate parties and he is not a member of Ocean Navi. 

Some information in our website is old and we apologize for not taking care of it timely manner. 


Mika Tokairin on behalf of Masayuki Moriya / Ocean Navi

Dean Summers Commentary

Dean Summers’ report on his experience attempting the Tsugaru Strait on five separate occasions, most recently on July 14, 2023.

‘I’ve made 5 attempts to swim the channel and each has been more difficult because of the nature of their organization. ‘I’ve made 5 attempts to swim the channel and each has been more difficult because of the nature of their organization. 

  • Ocean Navi demands full payment many months before a swim.
  • Costs have increased dramatically over my past 5 attempts and this year they include an overtime extra cost (similar to Catalina). 900,000 Y for 10 hours and then 20,000 Y per hour cash for the next 4 hours.
  • O.N. have initiated a 14 hour cut off time and the 1st swimmer of the season was stopped at 14hours.
  • A few weeks before my swim I was told that the coast guard have ruled that no swims start before first light and must be completed in daylight hours. This is a huge change from previous years and the core of the problem. Currents typically build up after daybreak and increase for the next 10 hours.
  • Slots have now shrunk to 5 day windows shared between two swimmers. This is a little confusing but the first three days of a slot is for the first swimmer and next 2 day for the second swimmer. If the first swimmer goes early (ie/ the first day) then the second swimmer has the rest of the 5 day slot. If the first swimmer hasn’t swam in 3 days they go home dry. 
  • Im told that they stack these 5 day windows back to back for the month of July only.
  • I was with Edie Hu when we were told that the fishermen would rather be fishing than escorting swimmers and it was increasingly difficult to find fishermen to support. We have no idea how much they are paid but there are always two captains, one on each of the two boats.
  • O.N. now only send one observer to Kodamori to liaise with swimmers and their teams while previously there had been three representiaves from O.N. The observers have been excellent and committed to the sport and in my view been used to shelter decision makers in O.N.
  • The contract we have to sign is confusing and continually being added to. Currently we are on its 6th iteration.
  • Just before the boat leaves we are shown paperwork titled “Pledge” and asked to fill in names and dates. It demands, along with other terms that a swimmer will not complain publically if they are pulled out if unsuccessful for any reason. “

Ocean-Navi – TSSA – Independent

Table of Ocean-Navi swims on their website vs. MSF, OWP, possible missing swim for first female see resources section.(1) Orange highlight over 14 hours, Start and Finish times being updated

Going Forward

We want the community to be informed. We also want to ensure there is a supportive environment for swimmers tackling this historic challenge.

If you would like to share any information or insights publicly, please comment below.  If you would like to share information or insights privately, please email

WOWSA’s Advisory Board will also be meeting in the coming days to discuss our research into Tsugaru Strait and determine potential courses of action, if any. The Advisory Board’s recommendations will be shared publicly.  


(1) Footnote

Photo credit: Ocean-Navi

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