The first thing to do is take down the leader of the Canalave City gym to unlock the ability to use the hidden move Surf outside of battle. In case you lose this ability, you can get it again by talking to Cynthia's grandmother in Celestic Town, who will give it to you after obtaining the information in the ruins.
After eliminating the gym leader, you can venture down the rivers of Sinnoh back to Valley Windworks. On the way to Valley Windworks you will have to go down on the bridge, where you will have to use surf in the water, to be able to go to Valley Windworks to the east. As you progress down the river behind Valley Windworks, you will be able to find a landing where the TM is.
In case you want to buy Thunderbolt, you will have to go to the Veilstone City warehouse, where on the third floor you can buy the TM for 3,000 PokéDollars.
That's everything you need to know about how to find TM24 Thunderbolt in Pokémon Brilliant Diamond and Shining Pearl, so now that we've reached the end of this article, we hope you get and get the most out of this item.