A new scheme offering information and discounts aims to help families explore Scotland's natural assets. Juliet Rix reports

We do as we're told, but in the end, it comes out of the blue. A large and leisurely grey back lifts above the surface, a long smooth curve and then a fin. "Cool," says 11-year-old Luke. And the back slowly dips out of sight again. We have seen a minke, smallest of the baleen whales; still, at up to 10m long, just a metre shorter than the boat we are in.

Bobbing comfortably engineless a few hundred metres off the coast of Mull, we pass a pleasant five minutes drinking hot chocolate, before a darker tighter curve breaks the calm sea surface - a harbour porpoise. Our skipper quickly drops a hydrophone over the side so we can hear the clicking of the porpoise's echolocation system as well as see it wheeling in and out of the water.

We have been lucky - a minke and a porpoise in quick succession. Lucky, but not exceptionally so. Certainly in the later summer months (which conveniently coincide with the school summer holidays) even this two-hour, child-oriented "Ecocruz" in sheltered waters almost always finds porpoises and often a whale.

We are out with Sea Life Surveys, one of more than 30 (mostly small and local) companies involved in the new Wild Scotland Passport, which provides information and discounts on a range of family-friendly visits and expeditions to see Scotland's exceptional wildlife. Scotland is home to the UK's largest bird of prey, the white tailed sea eagle, with an eight-foot wingspan, to some of the world's tamest sea birds, and to 20 species of whale and dolphin.

The whales have only been recognised relatively recently. When Sea Life Surveys began more than 20 years ago, they were accused of conning the public: nobody believed they were seeing minkes. Cindy is now so familiar to them that she calls them "Stinky Minkes". If you're downwind of a close one, she explains with relish, "its breath smells of rotten fish." Cindy certainly has a way with the information - and with kids.

Our Ecocruz is now chugging along the coast and Cindy turns our eyes to the shoreline: "This is Bloody Bay," she says and describes a 15th-century clan battle that turned the water red. Via a brief lesson in geology, we are back with the animals - a grey seal in full view just metres away, lazing on a concrete stump by a fish farm. Luke is transfixed by the shapes hanging in the water - orange lion's mane jellyfish with long tentacles (a less dangerous relative of the Portuguese man-of-war, he is informed) and the patterned translucent hemispheres of moon jellyfish. We pass a lighthouse designed by the grandfather of Robert Louis Stevenson (of Treasure Island), a waterfall, and a colony of shags (like cormorants), who can apparently dive up to 25 metres under the water. On this trip, there is never a dull moment.

The seal colony is empty of its 50-odd seals; they are out feeding, because our trip is later than usual due to earlier bad weather. But the lobsterpots, bated by Cindy with her leftover salmon sandwiches, contains two crabs, as well as some tiny, and remarkably cute, lumpsucker fish. These, to the kids' relief, are rescued from the deck and Luke holds the hermit crab while Cindy explains the sustainability of lobster pot fishing and the life cycle of crustaceans, before everything is carefully thrown back.

"That was brilliant," says Luke as we return full of fresh air, enthusiasm and loads of willingly absorbed information. And as we dock, Tobermory, the main (but diminutive) town of Mull looks picture-postcard lovely, with its semicircular harbour edged with brightly coloured houses. The town is well known to younger television viewers as Balamory (BBC2/Cbeebies) and Cindy also leads a half-hour Balamory cruise for tiny tots taking in the seal colony ("who can spot a seal pretending to be a rock?") and pointing out the individual houses of the Balamory characters.

Luke and Daniel, 14, are more interested in the sea eagles. Hunted to extinction a century ago but reintroduced in the 1970s, there are now 32 pairs in the UK (all in Scotland). Frisa, aged 13 (hatched on the island), and Skye, 11, nest each year on a Forestry Commission plantation in Mull. A consortium of the RSPB, Scottish Natural Heritage and the local community has set up a hide staffed by RSPB ranger, Dave Sexton, with two telescopes, and a close-circuit camera providing a "Nest Cam".

The two chicks (nicknamed Itchy and Scratchy) are still confined to the nest and can be clearly seen feeding and stretching their wings. Through the second telescope, the adults are usually visible perched like sentries on adjacent pine trees.

The children marvelled at the 18in "wing tip" feather Dave lets them handle, as well as the 4in-5in pellet full of gull bones. He showed us, too, the coloured tags that will be attached (harmlessly) to the chicks' wings when they are older, so that sightings can be used to track their movements. It was hard to drag ourselves away from the telescopes - until a midge cloud drove us rapidly into the car.

Our final trip was to Staffa and Lunga, 30-45 minutes by boat from Mull. On Staffa, we visited the bizarre basalt cavern that is Fingal's Cave, but the highlight was Lunga. An impressive colony of thousands of sea birds, mostly razorbills and guillimots, peppers the rocks of a dark granite gorge. However, it is the puffins that are the most magical.

From the boat we wandered up a short steep path to the top of a grassy cliff and there all along its edge were hundreds of puffins, completely unconcerned by our presence, even as we walked along just a metre from their burrows.

The thickening rain suddenly seemed insignificant and we sat down just a foot or so from the puffins and watched then carrying beakfuls of grass into their burrows and popping up again to look around. One little chap even waddled over to within a few inches, apparently to have a look at us.

They advertise this trip as "puffin therapy" - and it was. We arrived back, drenched and happy.

Give Me The Facts

How To Get There

The author travelled by train: GNER (08457-225225; www.gner.co.uk) and Virgin Trains (08457-222333; www.virgin.com/trains) operate services. Caledonian MacBrayne (0870-5650000; www.calmac.co.uk) runs ferries to Mull. A return costs from £47.50 for a car, adults £6.80 and children aged 5-16 £3.40.

Where to stay

Glenaros Lodge (01680 300301; www.glenaroslodge.net) offers b&b from £20 per person per night.

What to do

The Ecocruz, the Balamory Cruise, and four to six-hour whale watches are available through Sea Life Surveys (01688-302916; www.sealifesurveys.com) from Easter to October. The Ecocruz costs adults £20, children £16. The Balamory Cruise costs adults £6, children £4. The whale watches cost from adults £40, children £35.

Sea Eagles operates from April to July (01688 302038), adults £3, children £1.50. Staffa & Lunga (not recommended for toddlers) is organised by Turus Mara (08000 858786; www.turusmara.com) from Easter to October. It costs adults £35, children £18, families (two plus two) £95.

Further information

A Wildlife Passport is available free from Visit Scotland (0845-2255121;www.wild-scotland.co.uk) offering discounts and information on family friendly wildlife activities. Pack full waterproofs (including trousers and footwear), sunscreen, sunglasses, hat and binoculars.