The geographical setting of the Hawaiian Islands

Basic Geography of the Hawaiian Islands

The Hawaiian Islands are viewed as a result of a “hotspot” in the upper mantle – visualized as a sort of heat source in the upper mantle of the Earth over which the North Pacific tectonic plate has been moving for millions of years.  As the thin oceanic crustal plate has been moving northwestward, it has passed over a relatively stationary heat source in the upper mantle.  This, in turn has generated magma, that due to its lesser density, has migrated towards the surface resulting in occasional volcanic eruptions.  This simple conceptual model doesn’t answer many questions (like why are there discrete islands rather than one continuous ridge), but it is understandably hard to make direction measurements in the interior of the Earth.  The best source about the Hawaiian volcanoes and their monitoring is that from the United States Geological Service Hawaiian Volcano Observatory website.  The entire site has interesting information, at varying levels of detail but sufficient for nearly all natural history travelers.

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Basic geography map of the Hawaiian Islands showing each of the islands from one USGS website.

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Relief of the main Hawaiian Islands.  The yellow line, for scale, is 500km long (about 310 miles).  Flying is the most practical way to travel between the islands.

 

Logistics of getting to the islands

Most flights from the US mainland and elsewhere arrive to Honolulu on the island of Oahu.  Honolulu is the largest city in the Hawaiian Islands and receives by far the most tourists.  Other direct flights from the US mainland arrive to Maui, then Hawaii (hereafter termed “the Big Island” and then Kauai.

Travel between the islands is mostly by plane.  There are regional airlines that have frequent flights between all of the major islands.  It is more practical to fly between the islands and then rent vehicles on each island you visit.  Except for the Honolulu airport, other airports are relatively small and uncongested.  See this link for more information.  Monthly tourist statistics for the main islands are in Fig 2 and here.

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Fig 2.  Hawaiian tourism facilities by month for 2018.  From this site.

The main points from this figure are that 1) tourism is fairly constant throughout the year and 2) Oahu get much more tourism than the other islands.  Given that the Big Island is larger than all of the other islands combined, the “tourist density” is very low on the Big Island – at least compared with the other islands.

Accommodations in Hawaii are very expensive compared with the US mainland.  Expect to pay $150-200 or more for low-end accommodations (B&B’s, etc) – away from the beach.  Resorts can be two to three times this per night.

Traffic can be surprisingly heavy for the population of the islands.  There is not a grid-like network of roads like at most mainland destinations.  Each island has a coastal road that circumnavigates the island and this can become very congested near rush hours, if there is construction, or if an accident occurs.  In our relatively short recent trip to the islands we experienced heavy rush hour traffic on the Big Island in Hilo and along the Kona coast.  And on Kauai – “the Garden isle” – it took us 30 minutes to go 2 miles at rush hour.

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Near the Kona coast airport there are divided highways with plenty of traffic at certain hours.  Note this isn’t your “stereotypical” Hawaiian landscape.

Below we describe the basic geographical aspects of each of the main islands.  This includes simplified aspects of their relief, geology and climate.  More extensive discussions of geology and climate are discussed under their respective pages and flora and fauna are likewise covered on their pages.

Finding “Nature” in Hawaii

Finding natural areas in the Hawaiian Islands is not as simple as one might expect.  Yes, there are the national parks on the Big Island and on Maui.  But other islands don’t have national parks and many of the state parks are associated with beaches.   Waterfall-dominated parks do have trails, but nature is not the focus of such parks.

All Hawaiian Islands have forest reserves managed by the state of Hawaii.  These reserves may include introduced trees and are not managed to be strictly natural landscapes – though some are quite natural.  Hunting is allowed on weekends and hunters may be the most frequent visitors to such reserves.   It is suggested you wear bright orange clothing to be visible to hunters – exactly what a birder might not want to do!  The relatively recent Hawaiian State Natural Area Reserve system is attempting to strictly protect natural landscapes for biodiversity protection but these are often closed to public entry.

Below we quickly summarize our perception of highlights for seeing “nature” on the islands we have visited.

The Big Island (Hawaii)

During our Dec 2019 visit to Hawaii we spent 7 nights on the Big Island – all in the small community of Volcano – at the eastern entrance to Hawaii Volcanoes National Park.  This small town/village area is at about 3500 ft elevation so it is cool compared with coastal locations.  In addition, the trade wind flow ascends this side of the Big Island and it is very frequently cloudy with light rain.  Annual precipitation is near 140 inches per year, resulting in verdant landscapes.

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Hawaii Volcanoes National Park is our favorite area in the Hawaiian Islands to experience natural environments.  The combination of extensive trails through volcanic landscapes and sharp transitions between moist and dry forests, along with coastal and high mountain environments, allows for one to experience relatively natural and relatively uncrowded environments.  Because the Park’s attractions are quite distant (at least 80-90 miles) from the main touristic resorts on the Kona coast (west side) of the Big Island, fewer tourists visit the park, and many of those that do visit are “day trippers” or as part of tours.  These individuals are thus not present early in the morning or late in the day.  The lack of current volcanic activity (ending in late 2018) may have reduced present visitation numbers, though this is not clear.

Kilauea caldera looking towards Mauna Kea showing the many lava flows exposed in the caldera’s walls.

 

Mauna Loa in background with the Kilauea caldera in foreground with Ohia recolonizing the cinder field in front.

Ohia forest on aa lava off the Saddle Road near 5000 ft elevation

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Current map of Hawaii Volcanoes National Park provided at the entrance gate upon arrival.  Click for detailed view.

 

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Hawaii Volcanoes National Park “backcountry” trail map.  Click on map for larger view.  NOTE: some trails are closed due to the 2018 eruptions and earthquakes.

Maui

After the Big Island, Haleakala National Park on Maui is our next favorite area for observation of natural environments.  While there are fewer trails at Haleakala National Park and they are more strenuous, they pass through relatively natural high altitude landscapes.

The drawback of the Haleakala area is that it is far from tourist accommodations – requiring an hour or more drive from coastal resorts.  This makes getting an early start on trails difficult, and possibly forcing night driving on your return from the park.

The trails in Haleakala NP that descend into the “crater” are long and best suited to overnight hikes.  There are huts with bunks for hikers, as well as camping areas for backpackers, but these require reservations with the park service.

There are other areas on Maui that are worthwhile for naturalists to visit.  We did not drive the highway to Hana, on the southeast side of Maui, but this is where the moist forests are found.  However, accessing natural-state moist forest is not easy, as no roads or trails are open to the best natural moist forests. Likewise, in the Iao Valley State Park, few visitor’s explore the more remote parts of the West Maui Mountains because of the muddy/poor trail conditions.  Also, there are many non-native plants in the more touristic areas.

A more natural dry forest environment exists in the Ahihi-Kinau Natural Area Reserve, located on the southwest tip of Maui and containing the most recent lava flow on the island.  While you can walk on a trail over the lava flow to see stone constructs made by the original Hawaiians, you cannot access the best examples of dry forest remnants.

Finally, for seeing birds, the Kealia NWR is probably the best place to see wading birds.  It is a slowly recovering wetland that is being managed for wildlife (mostly birds).  Unfortunately, there are plenty of feral hogs and the ponds are clearly artificial.  Despite these aspects of the refuge the boardwalk along the beach and lagoon with its many educational plaques is excellent.  And for those wanting to see the Hawaiian Stilts and a few other endemic Hawaiian water birds, the location is good for stroll.  Just not worth coming all the way to Hawaii for.

silhouette of people on top of Haleakala just after sunset. Note the selfie-takers.

Silhouetted domes of various telescopes on top of Haleakala just after sunset. You cannot visit these telescopes; they are operated either by the US Air Force for space surveillance or the University of Hawaii.

Haleakala is a long drive from the resort areas on Maui – it is about 40 miles to reach the main visitor center that is at 7000 ft elevation.  It is another 3000 ft altitude gain to the upper visitor center and entrance trail into the main “crater” of Haleakala.  The road is very winding, with many curves – especially before reaching the national park.

Mauna Kea in distance (with telescopes) from Haleakala on Maui.

Mauna Kea in distance (with telescopes) from Haleakala on Maui. Small part of ocean between the islands is visible in the lower right.

Hiking trail switchbacking into the Haleakala crater. the descent in about 1000 ft.

Telephoto of hiker coming up the trail.

We did not extensively explore Maui, especially the moist areas on the eastern part of the island – the road to Hana.  However, finding natural moist forests on Maui (or on any of the islands) is not simple.  All Hawaiian Islands have forest reserves managed by the state of Hawaii.  These reserves may include introduced trees and are not managed to be strictly natural landscapes – though some are quite natural.  Hunting is allowed on weekends and hunters may be the most frequent visitors to such reserves.   The relatively recent Hawaiian State Natural Area Reserve system is attempting to protect natural landscapes but these are often closed to public entry.

Cinder cones within Haleakala crater from near the top of the Sliding Sands trail.

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Trail map for Haleakala National Park.   Click for larger image.

Kauai

We only spent 3 days on Kauai, so we could not sample all interesting natural areas.  We chose not to hike Alakai Swamp trail at 4000 ft elevation, known as the best birding location on the island and with unique wet bog plants,  due to the drizzly and rainy weather and also the condition of the trail (muddy).

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Oblique view of Kauai from the south, the airport is on the far right and Waimea Canyon is shown by the dashed curve.

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A view of western Kauai from the north, now with the Napali coastal cliffs and steep slopes shown (as well as Waimea Canyon).  The boundaries are approximate.

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A closer oblique view of Waimea Canyon from the south.

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This shows the location of the Kawai’ele Waterbird Sanctuary (rectangle, pointed to by arrow.

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Vertical view of the bird sanctuary.  Click for larger view.

The road ascending along the western side of Waimea Canyon, on the western side of Kauai, to the state park lookouts over the Napali coast is mostly a series of scenic viewpoints and doesn’t offer much information related to the the natural history of Kauai.  An exception to this is the inconspicuous (and very limited side-of-the-road parking) self-guided nature trail about half way up the mountain that focuses on a rare and endangered species of plant related to the Silverswords.

We visited the Kilauea Point National Wildlife Refuge, while mostly known for its historic lighthouse,  is known among birders for being the best spot in all of the (main) islands for seeing seabirds.  These include Laysan Albatross, White-tailed Tropicbirds, several species of Boobies and Frigatebirds.  The Nene is also conveniently seen here.

A second spot for primarily bird-watching is a restored series of ponds in western Kauai near the Air Force missile range.  The ponds (former gravel pit) have native coastal vegetation with identifying plaques and explanations of the importance of these wetlands.  Some of the endemic birds like the Hawaiian Stilt, hawaiian Coot and some non-endemic but native birds like the Black-Crowned Night Heron are present.  Nene also hang out in this area.

Napali Coast from the Kilauea Point lighthouse

 

Oahu

We did not visit Oahu – other than a short stop to transfer planes on our flight from Hilo on the Big Island to Lihue (Kauai).  However, since more tourists visit Oahu than any other island, we briefly describe some of its aspects here.  The reader can compare it with the other islands – and perhaps decide whether it should be a natural history destination.

We chose not to visit Oahu because of the additional time required, the congestion of Honolulu and elsewhere on the island, the lack of relatively pristine environments, the lack of higher mountains that allow for ascending about the trade wind clouds, the lack of recent volcanism etc.  You can see our perspectives…

 

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