Apart from the standard list of items to bring offshore (slippers, toothbrush, gamma radiation dosimeter), I would suggest the following items be included in your standard kit:
- chalk – to mark equipment / piping when you’re doing a bloomin’ P&ID site verification. Use it to mark flow direction, line numbers, dates, ‘Kilroy was ‘ere’ graffiti.
- tape measure – it’s useful if you ever need to find access way dimensions, level heights, plot plan area. And if you bring the metal one, it makes a cool defensive weapon and an interesting injury report (“cut caused by inadvert operation of the tape measure release button.”)
- laser pointer – this is controversial, but it makes line tracing (especially if the line is above you) a lot easier. Have two, in different colours. Purple for Mace Windu, red for Darth Vader.
- gloves – typically not standard PPE equipment.
- Notebook
- Pens – a lot of pens, approximately one per day at location. Mine keep on getting donated to the denizens of the deep, when they slip out of my shoulder pocket and through the grating.
- Camera – ease of documentation. Not only on site, but to make copies of documents when the photocopier is down, or there is no paper to be had.
What else do you like to bring? plumb-bob? Duct tape? Chewing gum?
Wata - Malaysian Oil and Gas Engineer 
Depending on what sort of surveillance. The last time I went offshore for laser scanning activity, I brought with me rolls of duct tapes to paste the targets for the laser scanning job. Marker pens are a must, too. A camera is crucial not only to take your glorious and “hensem” photos while offshore, but also for 3D modelling purposes once back onshore.
Mohd Shaza: My type of surveillance is what EPMI expects from its facilities engineers. If other readers have different definitions, that’s fine with me.
The most important use for camera is take a picture of the team with the platform in the background. Proof to boss you actually went to site…..
camera is your best friend..not forget to bring some a3 paper. In case u need to photocopy a lot of drawings.