Plant Cuttings

Forest of the sea: The remarkable life and imperiled future of kelp by David Helvarg, 2026. Island Press, an imprint of Princeton University Press.

There’s a saying in English, ‘out of sight, out of mind’ (Candace Osmond), meaning that when something is not seen, it is easily forgotten or ignored. It seems particularly apt when applied to kelp*, large brown seaweeds (‘macroalgae‘) (Alan Millar; Ole Mouritsen; Leonel Pereira, 2021). Although they may grow so dense that they have been described as ‘kelp forests’ (Selma Christensen et al., 2023), they live the days that remain left to them submerged beneath the ocean. Essentially out of sight of land-based human eyes**, kelp exemplifies the notion of ‘plant blindness’, “a tendency for individuals to overlook and underestimate plants” (Georgios Ampatzidis & Alexandros Amprazis, 2026). And that plant-ignorance is never good, neither for people, or the planet [Ed. – nor for the plants themselves, who are eminently worthy of our admiration and appreciation].

So much for the bad news. The good news is that Forest of the sea by David Helvarg [which book is here appraised] seems destined to right that wrong as it opens our eyes to these magnificent ocean-dwellers, and – in particular – the perils they currently face. Helvarg has set himself the challenge of making everybody much more kelp-aware.

Appreciation for Helvarg

Forest of the sea by David Helvarg is about people as much as the kelp (and it’s also about other seaweeds and marine organisms as well as that particular group of brown seaweeds). Although it features a good deal about the biology of kelp specifically, it’s scope is much broader – ecological – than that. In fact, it’s probably one of the most holistic-ecology books I’ve read for a long time as it interweaves stories about kelp, sea otters, sea urchins, abalone, fish, lobster, communities of people, climate change, commercial activities, all together in an interconnected and very satisfying whole.

Whilst it contains quite a lot of science***, reading Forest of the sea is neither difficult nor a chore. And that’s because it is so well-written. Variously part nature diary (Helvarg’s lyrical accounts of diving on coral reefs in Palau, and in kelp forests in the US are pure literary gold), part ecological text, part travelogue (the ‘kelp highway’ is given a good mention here), part history lesson (who knew there was such a thing as ‘the otter wars’?), and liberally sprinkled with a plethora of pithy pen portraits of people and ‘kelp personalities’, Helvarg’s book is awash with engaging – and compelling – story-telling. Throughout, Helvarg writes with humour and humanity. Emphasising that humanity, Helvarg incorporates many first-hand testimonies from the people who are daily working with, diving in, trying to save and restore, kelp, etc. And, with numerous mentions of different groups of indigenous peoples, and their traditional relationships with kelp and its associated community of animals, Forest of the sea is very much a ‘plants’-and-people book. All-in-all, Forest of the sea is a pleasure to read. Not only that, it tells a very important story that deserves to be much more widely known by all of us****.

Book’s subject matter in a nutshell…

And that story can be summarised simply as “kelp is the new coral” (which is also the title of chapter 8). By which statement Helvarg is “not promoting recreational kelp diving. Rather, I’m pointing out that the kind of degradation we’ve seen with coral reefs is now happening to kelp forests” (p. 177). Documenting that demise (which seems pretty comprehensive in some areas…), and highlighting restorative measures (many of which are encouraging…), is what Forest of the sea is all about.

Sadly, kelp is not as eye-catching and ‘exotic’ as coral reefs in the mind of the public, so its plight – which is as bad as that of warm-water corals (as the book makes abundantly clear) – has largely gone unremarked by the public at large. Yes, there is a band of global advocates for kelp preservation, conservation, and restoration (and Helvarg tells us plenty about the sterling efforts being undertaken in that regard). But, until the general public is mobilised to take an interest in the problem, there’s unlikely to be the pressure on governments to increase the action they may be taken to conserve and restore kelp cover. That is why we need books like Helvarg’s Forest of the sea. It is not just an account of what’s happened and what’s being done now, it’s a call to arms, for all of us to promote the cause of kelp – and more generally ocean – restoration. Why should we care enough to do that? Because, as Helvarg is at pains to point out, what’s good for kelp isn’t just good for the sea otters, it’s good for the oceans more generally, and the planet – and people specifically. Forest of the sea is a most impassioned plea.

You still need evidence…

However, an impassioned plea is one thing, it is so much better – and convincing – to have it backed-up by evidence. And that’s what’s missing in the book*****. No explicit sources are provided for any of the statements made by Helvarg. Yes, there’s a list of Recommended Reading*****, but that contains nothing to tell the interested, but rightly sceptical, reader if those provide any of the facts Helvarg quotes. In several places in-text there are indications of sources for facts stated, e.g., ”A summer 2025 report in Current Biology identified…” (p. 7); “An August 2025 report published in the journal Nature Ecology & Evolution identified…” (p. 60); and “according to a 2024 report in Ecology and Evolution…” (p. 207). But, without author(s), titles, volume and page numbers, it would be quite a challenge to unearth the relevant articles.

And statements such as, “A study published in 2023 on ScienceDirect…”, and “Another 2024 study, also published on Science-Direct [which is presumably the same as ScienceDirect, as laid-out above…]…” (p. 27) don’t really help us much at all because ScienceDirect is not a named journal but a “searchable web-based bibliographic database, which provides access to full texts of scientific and medical publications of the Dutch publisher Elsevier as well of several small academic publishers” (quoted from here). Hosting “over 18 million publications from more than 4,000 academic journals and 30,000 e-books”, finding the ones Helvarg used is challenging. Whilst it seems clear that Helvarg has had access to the relevant sources for many of his statements, it’s a great shame that he hasn’t shared that information fully with his readers (who should be suitably sceptical – and entitled to see such sources – to satisfy themselves that all that Helvarg has said is reported correctly, having already seen that two different figures are quoted for the number of kelp species – “more than 300 species of kelp” (p. 3), compare with “there are about 30 species of kelp” (p. 80)).

In many more places, throughout the text, interesting points are made or facts shared that have nothing stated by way of sources. And that – serious – omission is such a pity. It undermines all of the hard work that Helvarg has undertaken in writing this important book. If you want to persuade others of the importance of these submarine forests, and convince the sceptical of the damage being done to them by human actions, your argument needs to be water-tight.

Forest of the sea is a serious book about a serious problem. But, to be taken seriously, it needs to provide its evidence.

Summary

David Helvarg’s Forests of the sea does sterling work in ensuring that the plight of kelp – the ecosystem it supports, and its people-sustaining planetary relevance – are no longer out of mind (even if they may be out of sight for much of the time…). This is an unashamed love letter to kelp. Or, rather, a love letter to the human race about kelp. I urge everybody to read it, and become more kelp-aware.

* Strictly speaking, kelp is not a plant, but a stramenopile (Thomas Silberfeld et al., 2014). Nevertheless, as a photosynthetic alga, and particularly one with a structure that has root-like, stem-like, and leaf-like parts, it is sufficiently plant-like to be considered an honorary plant for this blog, and is as much a victim of plant blindness as any ‘proper’ plant.

** Hidden from sight that is unless they are uncovered at low tides [https://sussexkelp.org.uk/about-kelp], or washed up on the shore when broken off by storms, etc. (Rachel Lambert, 2017; Wendy Laurenson, 2020. Or one swims or dives amongst them.

*** Examples of some of the technical topics – which attests to the book’s serious scholarly nature – dealt with in Forest of the sea include: convergent evolution, macroalgae, pneumatocysts, Great Oxidation Event, keystone predator, matrilineal transmission, trophic cascade, megafaunal collapse hypothesis (AM Springer et al., 2003; Douglas DeMaster et al. (2006), iron fertilization, blue carbon, ENSO (El Niño-Southern Oscillation), urchin barrens, Pacific Decadal Oscillation, environmental DNA, and dark oxygen. Pleasingly, these terms are usually sufficiently well-explained in-text for the reader’s information.

**** To find out more about Forest of the sea, and read an extract from the book (and see some colour images of kelp…), see here.

***** Forest of the sea is not completely without sources, it includes 1.33 pages of Recommended reading. Primarily of books, the list is provided without any comment. We therefore don’t know if any of these items are sources for factual statements made in-text. Items there certainly don’t appear to include any of the scientific articles Helvarg alludes to in-text. But, importantly, this listing does include the Kelp Forest Alliance’s 2024 State of the world’s kelp forest report (p. 241) [downloadable from here, and with a commentary thereupon by Aaron M Eger et al. (2024).]

For some more kelp-related reading, you might like to look at the following articles: Olivia Ferrari’s “Sea Otters Have Helped Bolster California’s Kelp Forest”; Avery Schuyler Nunn’s “What Free Diving in a Kelp Forest Taught Me About an Overlooked but Incredibly Valuable Ecosystem”; Evan I Schwartz’s “Underwater Forests Return to Life off the Coast of California, and That Might be Good News for the Entire Planet”. For a perspective on “Ecosystem services, functions, and the value of intact kelp ecosystems”, see the scientific article by David R Schiel & Stephen R Wing (2026). For another perspective, on “The EU Nature Restoration Regulation as an opportunity for kelp forest conservation and restoration in Europe”, see Cristina Piñeiro-Corbeira et al. (2026). And for some thoughts on “Impacts of climate-driven loss of giant kelp forests on local dive tourism”, see Scott Bennett et al. (2026).

REFERENCES

Scott Bennett et al., 2026. Impacts of climate-driven loss of giant kelp forests on local dive tourism. Annals of Botany: mcag284; https://doi.org/10.1093/aob/mcag284

Georgios Ampatzidis & Alexandros Amprazis, 2026. Plant awareness disparity (lack of plant awareness). Encyclopedia 6(3): 63; https://doi.org/10.3390/encyclopedia6030063

Douglas P. DeMaster et al., 2006. The sequential megafaunal collapse hypothesis: Testing with existing data. Progress in Oceanography 68(2–4): 329-342; https://doi.org/10.1016/j.pocean.2006.02.007

Aaron M Eger et al., 2024. State of the world’s kelp forests. One Earth 7(11): 1927-1931; https://doi.org/10.1016/j.oneear.2024.10.008

Leonel Pereira, 2021. Macroalgae. Encyclopedia 1(1): 177-188; https://doi.org/10.3390/encyclopedia1010017

Cristina Piñeiro-Corbeira et al., 2026. The EU Nature Restoration Regulation as an opportunity for kelp forest conservation and restoration in Europe. Annals of Botany mcag166; https://doi.org/10.1093/aob/mcag166

David R Schiel & Stephen R Wing, 2026. Ecosystem services, functions, and the value of intact kelp ecosystems. Annals of Botany: mcag143; https://doi.org/10.1093/aob/mcag143

Thomas Silberfeld et al., 2014. An updated classification of brown algae (Ochrophyta, Phaeophyceae). Cryptogamie, Algologie 35(2): 117-156; https://doi.org/10.7872/crya.v35.iss2.2014.117

AM Springer et al., 2003. Sequential megafaunal collapse in the North Pacific Ocean: An ongoing legacy of industrial whaling? Proc. Natl. Acad. Sci. USA 100(21): 12223-12228; https://doi.org/10.1073/pnas.1635156100