Lerwick, Shetland Islands, Scotland

Presumably you are arriving on a cruise. Unless you have been specifically told that you are berthing then you will be anchored in the lee of Bressay light station, and tendered ashore.

That will obviously affect what time you actually have ashore.

There are taxis, but they will probably be under a lot of pressure on a cruise day, so best (probably essential to pre book).

In the time available I would suggest 3 things-
1. Take the ferry over from town to the island of Bressay. That is off the beaten (cruise path) and good for a gentle hike.
2. Bus (or taxi) to Tingwall turn, then walk back via the (now closed) Church, down the Tingwall Valley past the Loch to the old capital of Scalloway. Look around the town museum, learn about the Shetland Bus and see the outside of the Castle (the inside is closed for building work), hourly bus back to Lerwick Viking Bus Station
3. Bus every hour down to Jarlshof (just past the airport and Sumburgh Head light station

Thank you so much for the information! Appreciate it!

I'll just add that the Shetland Museum is within walking distance of the docking area if you are coming in on a tender. I found it very interesting. I enjoyed local food at The Dowry on Commercial St which also has a branch at the Museum.

https://www.facebook.com/TheDowryShetland/

Are you a fan of the Shetland TV show? You can walk to see the exterior of Jimmy Perez' house, lol. It is called the Lodberrie.

https://www.shetland.org/visit/do/wildlife/beaches/bains-beach

The Jarlshof and Sumburgh Head are excellent places to visit if the transportation works and if it's a pleasant day.

editing to add: One more thing...there are some awesome places to hike. Among the places I visited, I loved walking at the Eshaness Cliffs and across the Tombolo at St Ninians to walk around that isle but I think you'd struggle to do that unless you had a car.

There is a bus that goes to Sumburgh airport which will drop you near Jarlshof, a superb site.You can then walk on a good path up to Sumburgh Head with spectacular cliff scenery and puffins galore.Hugely impressive area. Walk back down but of course, check the bus times.

Use this site for journey planning, it’s very good…

https://www.travelinescotland.com/

If the archaeological site doesn’t appeal, St Ninian’s Isle circuit is easy and very, very beautiful but you would have to research bus times carefully.I had a car while on the island.

The Zet trans website is my go to for Shetland as you actually see timetables in tabular form.- https://www.zettrans.org.uk/
They are the Shetland integrated transport authority. Zet is short for Zetland, the old name for the isles.
They have their own app, which does not require data, once downloaded.
I was lucky enough to do a cruise ship excursion to Eshaness, directly after Covid, when all Cruise excursions were running in a bubble, so we went there to avoid any contact with the locals.
The local village hall was even opened to provide exclusive toilets for us to avoid using public toilets.
It is not a normal cruise excursion.