Mangrove Walk in Havelock Island, Andaman

The mangrove forests of the Andaman Islands

The Andaman and Nicobar Islands carry a large share of India's mangrove cover, and an unusually wide range of species for a group of islands this small. That is a big part of why the water around Havelock is as productive as it is.

Mangroves grow in the intertidal zone, in the band where the tide floods and drains and where fresh water running off the land meets salt water coming in from the sea. It is a narrow set of conditions, and only a small number of tree families have ever managed to live in it.

How a tree survives in salt water

Salt is the central problem. Ordinary trees die in sea water because salt pulls water back out of their roots. Mangroves get around it in three different ways, and different species lean on different ones.

The roots you will actually be looking at

Root shape is the easiest way to tell mangrove types apart, and once you know the four common forms you will spot them everywhere along the coast.

• Prop or stilt roots, the arching, spidery roots of the Rhizophora group, holding the trunk clear of the mud. They spread the tree's weight over soft ground and absorb the force of moving water, which is why these species sit on the seaward edge.
• Pneumatophores: the pencil-like roots of Avicennia that stand straight up out of the mud in dense fields. Mangrove mud holds almost no oxygen, so the tree sends these up to breathe. Small pores take in air while the tide is out, then seal when it comes back in.
• Knee roots. Bruguiera sends roots that loop up out of the mud and dive back down again, doing the same job as pneumatophores in a different shape.
• Buttress roots. Wide flanges run down from the trunk on species such as Xylocarpus, bracing a tall tree in ground that will not hold a deep root.

Seeds that germinate before they fall

A seed dropped into salt water and tidal mud has very poor odds. Many mangroves avoid the problem entirely by letting the seed germinate while it is still attached to the parent tree, then dropping a fully formed seedling. In Rhizophora these look like long green javelins hanging from the branches. When one drops it either spears into the mud below and roots on the spot, or it floats away on the tide, staying alive for weeks until it grounds somewhere it can grow. It is one of the few plants that gives birth rather than sowing.

Why mangroves matter more than they look

• They are the nursery for the reef. Juvenile fish and prawns shelter in the root tangle where larger predators cannot follow. A reef with mangroves behind it carries far more fish than one without.
• They lock up carbon. Mangrove ground stores several times more carbon per hectare than tropical rainforest, most of it in waterlogged soil where it does not break down.
• They hold the coast together. Root networks trap sediment and take the energy out of waves. After the 2004 tsunami, coastline sitting behind an intact mangrove belt came off better than coastline that had been cleared, in enough places across this region to be hard to argue with.
• They filter what runs off the land before it reaches the reef, which matters for coral.

What lives around the roots

• Mudskippers. Fish that spend much of their life out of the water, breathing partly through wet skin, walking on their front fins and defending small patches of mud. Nothing else on the walk gets as much attention.
• Fiddler crabs. The males carry one absurdly oversized claw and wave it to signal, in colonies of hundreds across open mud at low tide.
• Mud crabs and tree-climbing snails. The snails climb the trunks as the tide rises and come back down as it falls.
• Birds: collared kingfishers, egrets, herons and sea eagles all work the mangrove edges. If birds are your main interest, our bird watching walk goes after them properly.
• Monitor lizards, large and shy, usually seen heading away from you.

What your ₹2,000 covers

What to bring

• Water
• Insect repellent. Mangroves and mosquitoes go together, so treat this one as compulsory
• A cap or hat, and sunscreen
• Footwear you do not mind getting muddy, with a grip. Mangrove mud is soft and it stains
• Quick-drying clothes rather than anything you care about

Weather, tide and rescheduling

• Start time is confirmed the day before, once we have the tide.
• Heavy rain or an unsuitable tide means we move you to another slot during your stay.
• Full refund if no suitable slot is available before you leave.
• If you cancel 72 hours or more before, you get a full refund minus a 5% fee and GST. Inside 72 hours there is no refund. Walks between 15 December and 15 January are non-refundable. See our refund policy.

If you would rather see mangroves from the water than from the mud, we also run mangrove kayaking, which is a different experience with the same trees. The intertidal walk is the natural companion to this one.

Mangrove walk in Andaman: frequently asked questions