In recent years, the CLAMATO survey with the Keck-I telescope has been observing high area densities of z~2-3 star-forming galaxies spectra. This enabled a closely-spaced grid of sightlines that tomographically map the Lyman-alpha forest in the IGM at z~2.0-2.5. I will discuss the observations which have lead to the highest-redshift detection of cosmic voids and preliminary results for the cross-correlation with co-eval galaxies. Other applications include constrained realizations of the observed volume,
constraining galaxy-cosmic web intrinsic alignments, and cosmological parameter measurement. Finally, I will describe the future prospects of this technique including the Subaru-PFS IGM Tomography Survey, and the ambitious Billion Object Apparatus (BOA) of the 2030s.