Antonio de la Rosa on the three-month journey at sea. Photo / Supplied

A paddleboarder who set a new record after spending 76 days in the middle of the ocean has revealed the most disturbing part of his epic journey.

Spanish athlete Antonio de la Rosa became the first person to paddleboard across the Pacific Ocean solo on Saturday when he completed the 4750km trip from San Francisco, California, to Oahu, Hawaii, using a specially designed stand-up paddleboard.

He said the view was "breathtaking" but there was one thing he couldn't escape: plastic polluting the otherwise pristine ocean.

The endurance athlete said he saw plastic nets and other debris float past him every day of his 76-day journey.

And he said he hoped his record-breaking journey would bring attention to plastic pollution.

"The ocean is full of overfishing material, networks, plastics etc," de la Rosa wrote in a daily diary of his journey on Facebook, translated from Spanish.

"We must do something, it takes companies and multinationals to change their way of working and that they really commit to improving the environment and the cleaning of the oceans."

He said he tried to create as little waste as possible during the three-month journey, but some use of plastic was unavoidable for necessities in vacuum packs to protect them from the elements.

"I keep absolutely all (that) packaging and (they) end up in a recycling container in Hawaii, I assure you," he said.

De la Rosa set off from San Francisco on June 9 without a support vehicle and packed food, a desalinisation system for drinking water and other necessities on the 7.3m long paddleboard.

He said the fully-loaded paddleboard, which weighed more than 680kg, didn't have an engine. "My arms and my legs are my motor," he told CNN.

He said when conditions were good he could paddle up to 80km a day but didn't get much sleep as he needed to constantly check his GPS co-ordinates to make sure he was staying on course.

De la Rosa's warning about plastic in the ocean comes months after a study found the Cocoas (Keeling) Islands, a remote island paradise in Australian territory in the Indian Ocean, had 414 million pieces of rubbish wash up on its shores.

The rubbish included plastic straws, cigarette lighters, almost one million shoes and 373,000 toothbrushes, according to research led by Jennifer Lavers from the University of Tasmania's Institute for Marine and Antarctic Studies.

DÍA 15 - ASEO

DÍA 15 Muchos habéis preguntado dónde está el aseo en el barco, y casi todos lo habéis pensado…al final lo cuento en el vídeo. Hoy sin duda ha sido creo que el primer día que consigo un avance positivo hacia Hawái. Poco viento del Noroeste pero que tendía al Norte en algunos momentos, algo que me ha permitido remar en dirección suroeste todo el día, el mar ya se nota que no tira tanto para tierra, además hoy estaba bastante tranquilo, y parece que será así hasta el miércoles. Me noto con mucha más agilidad en el barco, entro y salgo de la escotilla como si fuera la puerta de casa, pero no pierdo la seguridad en ningún momento y cada vez que estoy fuera de la embarcación, aunque sea un día súper tranquilo mínimo tengo el invento en el tobillo puesto. Llevo 2 días con el curry puesto, un pez de plástico con anzuelo atado a un sedal de unos metros que voy arrastrando, pero la verdad es que no se ve un sol pez, muy diferente del Atlántico que me iban acompañado todo el tiempo. Espero pescar algo pronto que ya apetece. Sigue sin salir el sol, y van como 12 días, siempre está nublado con algún pequeño rayo de sol que entra entre las nubes, no llueve, con lo cual se agradece para remar con menos calor. Confiando que se mantengan las previsiones y pueda progresar hacia las islas con continuidad. Dejo de escribir que…me estoy cagando, je,je !!!!Vamossss!!! #pacificsupchallenge2019 #OceanDefender Meridiano Raidraid Leatherman @El Transistor Sea to Summit Iberia Sea Trek Kayak and SUP Center ocean52 Galletas Gullón Rimspolish S.L. Sps Stand Up Paddle Kundaka Sinergia Racing Group SLU Teva Posovisual @4050Adventure Meridiano Águilass Ciclo Lodge - El Nevero Olight España Katadyn Outdoors

Posted by Antonio de la Rosa on Monday, 24 June 2019

A recent global estimate suggested there were 5.25 trillion pieces of plastic ocean waste spread across the world's oceans. That's more pieces than there are stars in the Milky Way.

"Global plastic production has increased exponentially over the last 60 years," Ms Lavers' study noted.

"Nearly half of all plastic manufactured during this time was produced in the last 13 years, with 40 per cent of items entering the waste stream in the same year they were produced."