# Extending tether up to 4km **URL:** \ **Category:** General Discussion\ **Tags:** ardusub\ **Created:** [July 5, 2021, 5:05pm UTC](https://discuss.bluerobotics.com/t/extending-tether-up-to-4km/10096 "2021-07-05T17:05:37Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![sudheeshk](https://avatars.discourse-cdn.com/v4/letter/s/71c47a/32.png) [@sudheeshk](https://discuss.bluerobotics.com/u/sudheeshk)\ **Post date:** [July 5, 2021, 5:05pm UTC](https://discuss.bluerobotics.com/t/extending-tether-up-to-4km/10096/1 "2021-07-05T17:05:37Z")
Hi everyone, I found a tweet regarding 2km [aquaduct inspection](https://twitter.com/bluerobotics/status/981724225315659777). I would like to know the tether technology used here. I am also looking to extend my tether length to a distance of 4km . Can anyone please help me to explain tether extending technology? Thanks -sudheesh ---
**Author:** ![spotxuv](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/spotxuv/32/1112_2.png) [@spotxuv](https://discuss.bluerobotics.com/u/spotxuv)\ **Post date:** [July 5, 2021, 11:16pm UTC](https://discuss.bluerobotics.com/t/extending-tether-up-to-4km/10096/2 "2021-07-05T23:16:30Z")
Most likely fiber optic I would imagine. There are a few posts on here on how to do it. Prices have come down considerably and it is not technically challenging to do yourself. ---
**Author:** ![EliotBR](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/eliotbr/32/6937_2.png) [@EliotBR](https://discuss.bluerobotics.com/u/EliotBR)\ **Post date:** [July 6, 2021, 12:45am UTC](https://discuss.bluerobotics.com/t/extending-tether-up-to-4km/10096/3 "2021-07-06T00:45:54Z")
Hi @sudheeshk, [Here](https://discuss.bluerobotics.com/search?q=long%20tether)’s a relevant forum search link. [This post](https://discuss.bluerobotics.com/t/run-bluerov-over-fiber-optic-tether/3355) looks to be particularly relevant, but others there likely are too.